Why is ７元/并 written instead of ７元/瓶? A photo from the campus shop:


  
  (large image)


I transcribe and translate this to:


  纯享促销　７元/并
  Purejoy promotion: 7 yuan/bottle


(Here, Purejoy (纯享 chúnxiǎng) is a brand of yogurt.)

I'm confused about ７元/并, and in particular why 并 (bìng) = "and" is written and not 瓶 (píng) = "bottle".

Question: Why is ７元/并 written instead of ７元/瓶?

Possible explanations:


并 is an abbreviation for 瓶 (which I think is the most likely case).
It's just incorrect.
A unit of this product is called a "并", which I haven't heard of before.
I'd say both you 1 and 2 apply here.

It is is an "abbreviation". A lot of characters can take a more simple form in handwriting, to make writing easier. It is not a correct form. It is not standardized.

Some of the character forms come from an abandoned simplification scheme in China: https://en.wikipedia.org/wiki/Second_round_of_simplified_Chinese_characters, some of them are just made up in daily life.

I'd say I would treat this as incorrect. I do not have much difficulty recognizing the label, with the very specific context where it is used. But without the context, I'm not sure if I can recognize it as a simplification of "瓶".