When I was growing up 90-ies, a mix of using public metro and buses to roam the city (since I was in second grade, when I was allowed to take metro to do afterschool karate) and spending summers in various countryside locations where my grandparents resided was a good mix.

I disagree that the kids need or want to roam without grownups all the time. Grownups are not the problem. Kids are fun for the parents, the company of parents and their peers is kinda amazing.

Systems and institutions are the problem. When kids are stuck in the daycare or school, in a very limited space, grownups are stuck at the office and grandparents are in a different state for tax purposes - that is the problem.

I don't know if this is true, but Patagonia claimed at some point that they used to maintain daycares and allow kids to roam the campus...