You never see gas pumps on their own, they’re always attached to some sort of store, and from what I’ve heard has makes very little profit but brings customers so they’re both pretty closely tied together.

Yes I’ve never walked to the local gas station to buy gas but I’ve walked to the local gas station plenty of times to buy bananas, cigarettes, and various snacks. I feel like they probably asked “gas stations” specifically because it was a more familiar way to say “convenience stores” because in practice most Americans don’t visit standalone convenience stores much (and people probably think of the ones that cater specifically to alcohol/cigs/sketchy lottery tickets).