Economics and receipts:
Why aren’t physical receipts always opt-in?”
As it happens, there’s an easy answer to this question: Because except in a few places (such as taxi cabs and hotels), the receipts aren’t mostly for you. They’re for the employer.
Employers know that it’s harder to steal if customers get receipts for their purchases, and so they’re willing to even offer a purchase for free if you don’t get one.
Also see this additional post on the same topic from an economic blog.
Both are worth the quick read and will increase your economic understandings around retail business!