You're more thinking suburban, or super rural. I grew up in a rural Welsh town (~3000 people), and was is walking distance of basically everyone we knew. I walked to school, to the pool, to the shops, my friends, everything.
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...
> But so glad we stayed in London
So I figure they are UK based and not in North America.