The not sure about the multi purpose thing- it might be prohibited by zoning in a lot of spaces by master plans, but it’s been actively encouraged for the last 10-20 years most places I’ve been, at least in infill areas. Also, the lack of “multi-purpose” development can be misleading, as “good” zoning does mix in commercial lots with housing, but they end up developed separately on different lots. The suburban development I live is walking distance to a shopping center with a grocery store, several restaurants, a services, and a park. That’s not 100% common here, but it wasn’t hard to find. The cost was reasonable to, at least until 2020 made the entire market go crazy, regardless of walkability.