Americans don't live in cities, or in towns, or in villages. They are farmed in facilities called "housing developments", where there are no stores.
A developer purchases large plots of agricultural land, and colludes with government to put a sprawling system of widely-separated four- to six- lane roads through it (often by widening and paving country roads until they are unrecognizable). Then, to hide this ugliness and block the resulting noise, they ring their newly-acquired fields with large earthen berms, which they cover with evergreen shrubs and chemically-treated wood-chips. At gaps in the berms they put gatehouses, with unarmed guards. Within these fortifications, they then build fanciful, curvilinear, branching systems of slower roads, like the endoplasmic reticulum of a cell, and around these fractal structures they put large, cheaply-constructed houses and driveways, which sell for $800k and above. Compared to the cities nearby, this is affordable.
Outside the berms, on the other side of the stroads, often without sidewalks, are, at best, strip malls, and, at least as often, are instead big-box stores surrounded literally by acres of blacktop parking lot. An "acre", you may recall, used to mean that which a man could farm in a day. Not this.
Now suppose you find yourself inside one of those houses inside the berms, and that you want to buy a vegetable. As the crow flies, it's possible that you are only a mile and a half from the nearest supermarket (not a very short distance, but achievable). But to get there by walking along the roads, you must first get to the gatehouse along the berm (which may or may not be in the direction of the store), and, to get there, you must traverse this fractal system of roads. The arclength may exceed the Euclidean distance from A to B by a factor of three or more. Either that, or you must violate peoples' sacred property, by cutting across yards and next to houses (which are not very far apart), and then finally scramble over the berm, amidst a shower of wood-chips.
Having achieved your escape from the "community", you must then find a way to cross four lanes of 45 MPH traffic (on a slow day). If you are lucky, there is a sidewalk, so you can walk half a mile to the nearest crosswalk. You do this separated from the whizzing death-machines by about the eight inches of grass that separates the sidewalk from the road. Do not let your mind wander. Keep your arms and legs inside the pathway at all times.
Upon finally crossing the street, you finally enter the shopping complex. It is surrounded by parking lots. Sweating and relieved that you have gotten this far with your life intact, you step into the air conditioning.
Then you buy that one vegetable you wanted for your supper, steel yourself, and conduct your return expedition.
Which, of course, is why you don't just buy what you need for today's supper. No, you didn't walk there at all. You drove there in a car, loaded the trunk with food for at least a week, and drove it home, to be preserved in your oversized fridge. Because venturing out in all that is a chore.
Back within your "community", there may be a nice, parklike atmosphere, full of what look like walking paths. But you may find that this is actually a golf course around which the houses have been built, and that -- ostensibly for safety from golf balls, or perhaps from golf carts -- these paths are often closed, in principle, to the "little people" who merely live there without additionally paying to whack a ball around. There are then petty conflicts between the golfers who have purchased special rights, and the simple pedestrians, who have the unseemly desire to locomote with their God-given feet.
An overwhelming proportion of the American landscape is like this. It can hardly be described as a culture or a way of life. It's just what people do when they have no identity and no ambition to create a worthwhile future. These people are deskilled, demoralized, and incapable of anything but consuming garbage.
A friend from Europe used to complain that, in America, the cows just stand there, whereas in Poland, the cows were mischievous and frisky. The process of domestication is further along in the US, and it degrades the people as much as it does the cows.
The good news is that these people will not have grandchildren and their houses will decay within 100 years. The bad news is that a shithole mess is going to be left behind.
Anyway, that's why they don't walk to the grocery store.