People can't really though, because of zoning and government planning. Like even if you wanted to make an area more walkable by inviting, say, a corner grocery store to set up shop in your neighborhood, usually you can't, because of single-use zoning.
And before you say, "well then just move to the city center!" perhaps you should consider that we're talking about a very common urban form across the world that is strikingly uncommon in the US due to government forces? Not exactly "people making their lifestyle preferences", more like "government imposing lifestyle preferences", and it's mostly just due to cultural momentum at this point.