question: How do supermarkets not detect your stuff as stolen if you buy multiple of them?
comment: Most products like that don't have security tags. Honestly, the only food product I've seen with a security tag is meat.
passages: Section::::Methods of theft prevention.:Security tags.
  
  Security tags are devices that are attached to products to prevent shoplifting and are often used in conjunction with an Electronic article surveillance system. SelectaDNA or Smartwater are such security tags - a forensic fluid which contains millions of tiny fragments which have a unique number called "SIN" ("SelectaDNA identification number"), and registered in a national police database together with the owner's details, is etched into each of those particles.
  
  Section::::Methods of theft prevention.:Tracking software.
   The possession of shoplifting tools (e.g. lined bags or wire cutters to cut bottle tags) can lead to the suspect being arrested for suspicion of theft or "Going equipped for stealing, etc." within the UK judicial system.
  
  In summary, while even the least expensive EAS systems will catch most occasional shoplifters, a broader range of measures are still required for an effective response that can protect profits without impeding sales.
  
  Section::::Discussion.:Tags containing alarms.
   The degree to which the purchasers of the stolen goods know or suspect that the items are stolen varies. If a purchaser buys a high-quality item for a low price, in cash, from a stranger at a bar or from the back of a van, there is a higher likelihood that the items may be stolen. On the other hand, if a purchaser buys the same high-quality item for the standard retail price from a used goods store, and obtains a proper receipt, the purchaser may reasonably believe that the item is not stolen (even if, in fact, it is a stolen item).
   To prevent theft, and assist in locating stolen objects, goods may be marked indelibly or undetectably so that they may be determined to be stolen, and in some cases identified. For example, it is sometimes arranged that stolen banknotes are marked with indelible dye to show that they are stolen; they can be identified by their unique serial numbers. Announcing that cash machines were fitted with sprayers of SmartWater, an invisible gel detectable for years, to mark thieves and their clothing when breaking into or tampering with the machine was found in a 2016 pilot scheme to reduce theft by 90%.
   Section::::Discussion.
  
  Section::::Discussion.:Occasional versus professional shoplifters.
  
  EAS systems can provide a solid deterrent against casual theft. The occasional shoplifter, not being familiar with these systems and their mode of operation, will either get caught by them, or preferably, will be dissuaded from attempting any theft in the first place.
   Hard tags, typically used for clothing or ink tags, known as benefit denial tags, may reduce the rate of tag manipulation. Also, shoplifters deactivating or detaching tags may be spotted by the shop staff.
  
  Shoplifting tools are illegal in many jurisdictions, and can, in any case, serve as evidence against the perpetrators. Hence, informed shoplifters, although they decrease their risk of being caught by the EAS, expose themselves to much greater judicial risks if they get caught with tools, booster bags, or while trying to remove tags, as this shows intent to steal.
   The platforms described above all operate in bulk mode, without needing to single-file product prior to inspection. In contrast, a sixth type of platform, used in the pharmaceutical industry, is a single-file optical inspection system. Although these sorters are effective in detecting and removing foreign tablets and capsules and defects based on differences in size, shape and color, they have not been widely adopted due to the high capital costs, low throughput and slow changeover, compared to the belt sorters for tablets, capsules and softgels.
  
  Section::::Platforms.:Mechanical graders.
   Efficiency is an important factor when choosing an overall EAS solution given that time lost attempting to deactivate labels can be an important drag of cashier productivity as well as customer satisfaction if unwanted alarms are caused by tags that have not been effectively deactivated at the point of sale.
   One significant problem from source tagging is something called "tag pollution" caused when non-deactivated tags carried around by customers cause unwanted alarms, decreasing the effectiveness and integrity of the EAS system. The problem is that no store has more than one system. Therefore, if a store actually has an anti-shoplifting system to deactivate a label they will only deactivate the one that is part of their system. If a store does not use an EAS system, they will not deactivate any tags at all. This is often the reason why people trigger an alarm entering a store, which can cause great frustration for both customers and staff. The problem is most evident in shopping malls where customers wander between stores.
   While the processes these internet thieves use are abundant and unique, one popular trap unsuspecting people fall into is that of online purchasing. This is not to allude to the idea that every purchase one makes online will leave them susceptible to identity theft, but rather that it increases the chances. In fact, in a 2001 article titled “Consumer Watch”, the popular online site PC World went as far as calling secure e-shopping a myth. Though unlike the “gateway” attacks mentioned above, these incidents of information being stolen through online purchases generally are more prevalent in medium to large sized e-commerce sites, rather than smaller individualized sites. This is assumed to be a result of the larger consumer population and purchases, which allow for more potential leeway with information.
   Prior to this, 1D retail barcodes were used that only offered limited protection as they did not cover all packaging on products. 2D barcodes meant that lids, sleeves, pack could all be identified by a barcode scanner to check that the product is packaged and dated correctly. In 2009, Marks and Spencer introduced a code of practice for the labelling of products that stipulated an autocoding system must be used on every production line. In 2013, it was estimated that autocoding software protects over 1500 lines in the United Kingdom; the largest supplier is Olympus Automation, which protects 723 food production lines.
   The shielding technique is well known amongst shoplifters and store owners. Some countries have specific laws against it. In any case, possession of such a bag demonstrates a prior-intent to commit a crime, which in many jurisdictions raises shoplifting from misdemeanor to felony status, because they are considered a "burglary tool." 
  
  To deter the use of booster bags, some stores have add-on metal detector systems which sense metallic surfaces.
  
  Section::::Discussion.:Jamming.
   Tags can be equipped with a built-in alarm which sounds when the tag detects tampering or unauthorized removal from the store. The tag not only triggers the store's electronic article surveillance system, but also sounds an alarm attached to the merchandise. The local alarm continues to sound for several minutes after leaving the store, attracting attention to the shopper carrying the merchandise.
  
  Section::::Discussion.:Installation costs.
  
  A single EAS detector, suitable for a small shop, is accessible to all retail stores, and should form a part of any coherent loss or profit protection system.
   The Metropolitan Police of Greater London, in conjunction with the SmartWater company, had as of 2017 fitted suitable detectors in all custody areas, and supplied them to patrol staff; prisoners are routinely scanned. They said "criminals contemplating attacks on Co-op ATMs [which are fitted with SmartWater sprays] should take note".
  
  Another area that has used the 'SmartWater Strategy' is Nottingham in England, where 56,000 homes had their property marked with SmartWater and covert operations using SmartWater were instigated by the police. There has been a reported 40% reduction in burglary since the start of the initiative.
   Section::::Solutions.
  
  Solutions involve "all phases" of product production, packaging, distribution, logistics, sale, and use. No single solution is considered as "pilfer proof". Often, packaging engineers, logistics engineers, and security professionals have addressed multiple levels of security to reduce the risk of pilfering.
  
  Each situation is unique. Some considerations have included:
  
  BULLET::::- Identifying who a potential pilferer might be: an internal employee, security guard, truck driver, delivery person, receiver (consignee), organized crime, etc. Engineers usually start with knowing what level of knowledge, materials, tools, etc. might they have.
   The timing of detection surveys and location scans is critical to success, and varies with the type of location being scanned. For permanent facilities, scans and surveys must take place during working hours to detect remotely switchable devices that are turned off during non-working hours to defeat detection.
  
  Section::::Countersurveillance by countries.:United States.:Methodology.:Devices that do not emit radio waves.
  
  Instead of transmitting conversations, bugs may record them. Bugs that do not emit radio waves are very difficult to detect, though there are a number of options for detecting such bugs.
   Radio-frequency identification chips are becoming more common with the introduction of smart labels that are used to track and trace packages and unit loads throughout distribution. Newer developments include recording the temperature history of shipments and other intelligent packaging functions.
  
  RFID can be integrated into labels: Smart labels.
  
  Section::::Security.
  
  A variety of security printing methods, security holograms, and specialized labels are available to help confirm that the product in the package is not counterfeit. RFID chips are being used in this application also.
  
  Electronic article surveillance (on the product or on the package) is used to help counter shoplifting.
   Coupled with intelligent software, sorters that feature cameras are capable of recognizing each object's color, size and shape as well as the color, size, shape and location of a defect on a product. Some intelligent sorters even allow the user to define a defective product based on the total defective surface area of any given object. They use high beam infrared laser beams to show the laser on the beam.
  
  Section::::Sensors.:Lasers.
   All UK Police forces, including the Metropolitan Police Service actively check IMEI numbers of phones found involved in crime, against the National Mobile Property Register (NMPR). The NMPR draws its information from many property databases. One of the databases consulted is Immobilise, which allows optional (and free) registration of devices by the public. Such registration ensures that a device coming into police possession may be easily reunited with its registered owner.
   BULLET::::- Security Layer 2: Issuance Check Out/In. When an asset is removed from inventory, we know it has been removed from shelf, but ownership has to be transferred from a “storekeeper” to a new owner, a soldier or guard or asset guardian. This is done using ruggedized Apple iPads known as gRaps that have a RuBee embedded reader. Tags are read as the asset is passed across the check out counter.
   There is one checksum item per contiguous run of allocated blocks, with per-block checksums packed end-to-end into the item data. If there are more checksums than can fit, they spill rightwards over into another checksum item in a new leaf. If the file system detects a checksum mismatch while reading a block, it first tries to obtain (or create) a good copy of this block from another device if internal mirroring or RAID techniques are in use.
   Shoplifting may be prevented and detected. Closed-circuit television (CCTV) monitoring is an important anti-shoplifting technology. Electronic article surveillance (EAS) is another method of inventory protection. Radio-frequency identification (RFID) is an anti-employee-theft and anti-shoplifting technology used in retailers such as Walmart, which already heavily use RFID technology for inventory purposes. Loss prevention personnel can consist of both uniformed officers and plain-clothed store detectives. Large department stores will use both and smaller stores will use one or the other depending on their shrink strategy. Store detectives will patrol the store acting as if they are real shoppers.
   The situation is further complicated by the concept of recklessness or wilful blindness to the circumstances; either will be treated as a belief that the goods are stolen. Thus, "suspicion" will be converted into belief when the facts are so obvious that belief may safely be imputed. So if the defendant bought goods in a pub or a dark alley for a fraction of their true value and it is clear that identification marks or serial numbers have been erased, any denial of belief by the defendant would not be credible.
   APT's can often gain access to sensitive information by physically tampering with the production of the product. In October 2008, European law-enforcement officials "uncovered a highly sophisticated credit-card fraud ring" that stole customer's account details by using untraceable devices inserted into credit-card readers made in China to gain access to account information and make repeated bank withdrawals and Internet purchases, amounting to an estimated $100 million in losses.
  
  Section::::Risks.
   Also a new form of concealment device, mock cans of various household chemicals or food and drinks can be purchased. A wide variety of commonly used personal care, household products and food containers with removable tops and bottoms are available. Valuables can be discreetly stored inside these lookalike containers and kept in their seemingly rightful places. Each of these diversion safes are indistinguishable from the genuine product, and can thus avoid detection, and they may even be weighted to feel full.
  
  Section::::Examples.:Coins.
  
raw_presuppositions: Supermarkets can detect your stuff as stolen. Supermarkets not detect your stuff as stolen if you buy multiple of them.
raw_corrections: Supermarket products do not have security tags, the exception is sometimes meat. Most products don't have security tags.