In a grocery story, one must pay for something before one consumes it. It's very easy to forget about something you intended to pay for, but forgot about -- stuff on the bottom of the cart, a pack of gum in the pocket, or a candy bar for the kids. The profit margin in grocery stores in very small, something like 3%. In a restaurant, the proprietor takes it on faith that customers will pay after eating, but you're usually in a somewhat confined, visible area, in view of other customers and restaurant staff. The best policy when shopping is to just go through the check-out line, pay for the item first, and preferably consume it outside the store to avoid any complications.
Blaming a city for its history is like blaming someone for the wrong eye color.
I'm afraid I do drink too many sodas, even if they are sugar-free and mostly caffeine-free. Have noticed a deterioration on my teeth from the acid.