Well, part of the family-unfriendliness is competition for cities' limited housing supply.

If a family with two adults and three children wants a 3-bedroom property, their budget depends on two adults' salaries minus the costs of three children.

On the other hand, if it's house-shared by four childless adults in their mid 20s, their budget is four adults' salaries, with none of the costs of children.

Lots of cities manage to do well with children; New York is an above-average performing urban school district with a million kids enrolled.

The problem is that with the rise of housing as an investment vehicle, cities have rapidly increased in price. In most countries housing is not a high-yield investment like stocks, it's a safer, low-yield investment like bonds. REITs have managed to destroy the goal of affordable housing for most people.

I wouldn't blame it on REITs but the vastly greater real lifetime income of the previous generations. Wages have been declining since the 70s.