No pre-set plan, no parental supervision, just a “I’m going to go meet my friends on this summer day, I’ll be back before dinner.” For purposes of illustration, assume these kids are aged 9-14, or thereabouts. Too young to drive, too old to be doted over every minute of the day.
If you would (and I hope you would!), would their friends’ parents? Would they be able to go casually knock on their friends’ doors (or even neighbors’ doors), be it biking or walking, and socialize, like kids do?
My guess is probably not. And that’s not the kids’ doing— that’s OUR doing. If parents really wanted their kids to go outside and explore, that would be the norm. But for far too many kids it’s not, because parents don’t want it to be: they’re worried about their kid getting hit by a car, kidnapped, getting in trouble, learning a lesson, the list goes on and on. The built environment reflects that kids are not expected to be outside, as if we’ve kid-proofed it. And so even if you want your kid to play outside, no one else is, and of course no kid wants to play alone!
Ironically, you would probably see more kids out and about, safe to be kids, in gasp New York City than in “safe” suburbia, from my own anecdotal experience.