If only builders could figure out some way to consolidate multiple living units under single roof, with shared building systems. Maybe something in the vertical dimension?

Oh no, but this might mean a hideous three-flat on my otherwise perfect block of identical white-picket-fences! Or God forbid, a duplex

And you know what kind of people live in apartments...

(That being me and most every other person in my neighborhood lol; we're all such animals, us apartment-dwellers, i can see why people would hate having young families, retired couples, and single professionals living on their street! We're a constant stream of boring mediocrity!)

Sarcasm aside: the best neighborhoods are always where there's a mix of housing and easy access to entertainment and chores. The suburbs i grew up in don't make the cut, but every neighborhood I've inhabited since--from college town "city centers" to quiet corners of the north side of Chicago--this is the common factor. Whether i was in a house, an apartment, a duplex, whatever, the good ones are where there's a real mix of housing stock, incomes, family situations, etc and you can get to a grocery store, pharmacy, doctor, or whatever in under 10 minutes, bonus points for being open at night. Visiting family in American exurbs is a major exercise in patience and planning (and driving)

That would violate many local zoning laws. NIMBY!