I like the idea of walking 15 minutes to get all the things. But man when I think of the costs involved in making sure there is a High School (in the US they tend to be large and draw from a distance) within 15 minutes of everywhere (no small cost to drop in a high school somewhere), or plop down a grocery store in a neighborhood ... that sounds both super expensive and politically difficult, and for some good reason…
> a High School (This is going to sound like we're playing Sim City 2000) but don't forget to add a hospital (a proper one, with an emergency room), a fire station, a police station... > a grocery store Are there many neighbourhoods which don't already have some kind of grocery store?
That's probably part of a shift over time. In general, we probably have more relatively large but spread out businesses than little mom and pop places on every corner.
(This is sort of a US comment. There seem to be more serviceable smallish grocery stores in Europe that are in between a supermarket and a convenience store. That's less common in the US other than one-off markets and sometimes downsized chain grocery stores.)