Why is a barcode called a “proof of purchase” even though it’s there before you purchase it and remains whether you actually purchased the item or not?

Question

Basically, the title. Why is a barcode called a proof of purchase, even though it’s usually printed on the item and is still there even if you have stolen said item?

In: Economics

Answer 1

The barcode is called proof of purchase not because it is actually the thing that proves you purchased it, but because it has the ID of the item on it. So when the barcode is scanned, its ID is removed from the “stock”. And in an extreme case, if you were accused of stealing an item, they can scan the barcode and see that its ID WAS infact purchased. It is the only way to PROOVE you purchased that specific item.