Were you actually visiting what Americans would consider a grocery store?

I'm not saying this is specifically the case for you, but it is remarkably common for visitors from other parts of the world to visit, go into what we consider a "convenience store", and then be confused that there's basically nothing in terms of actual groceries in there, with probably 80%+ of the "consumable" shelving devoted to snack/"junk" items.

Those stores are intended pretty much entirely for stuff people want while on the go, and the few "groceries" they stock are basically aimed at the kind of things a drunk/stoned person is craving at 3AM when nothing else is open (say, a frozen pizza), or the few things you might run out of by surprise in the morning/when about to eat and be willing to greatly overpay for being able to grab somewhere close by before your meal/schedule is ruined. (ex: milk, condiments, maybe eggs).