I think this sort of small discount is mainly aimed at people who were going to buy the item and eat it immediately regardless. If there's more than one tuna an

I think this sort of small discount is mainly aimed at people who were going to buy the item and eat it immediately regardless. If there's more than one tuna and egg sandwich on the shelf, it doesn't really matter to you which one you buy, but the store would rather you choose the one that expires sooner so they don't have to throw it out.