> If you live in a pre-car American town

Technically it was established before the automobile, but its tenth of a mile downtown commercial strip is the only remaining remnant of that. For all intents and purposes, it was built to "modern" standards, which is to say that its density is on par with the average American suburb. – To be fair, the streets and sidewalks are sensibly laid out. Some of those winding maze suburbs would take days of walking just to get out of the maze. That certainly helps.

By definition, urban requires at least 1,000 people per square mile at minimum. Any less than that and a place is well and truly rural by every account. Even at that minimum density, unless the town is literally a straight line, most everything should still be reasonably walkable.

The difference is really only that people in towns of 3,000 people want all the jobs, services, and amenities as possible. Whereas suburban folk fight tooth and nail to keep it all out. But the question is: Why? Why wouldn't you want those things nearby, most especially when you are complaining you can't afford transportation to those amenities where there are found elsewhere? What's the appeal of being shoved up tight against your annoying neighbour and to have nothing else?