Contrast my experience nearly 60 years ago in a small US town of ~35,000:
Once I had a bicycle I had almost complete freedom of movement. My buddy and I would cycle everywhere we could within about a 20-mile radius, out into the countryside, to the rivers and into the downtown urban area on our own. We also had large forests nearby and would wander afoot into those forests and stay out for half a day with no worry by us or our parents. To get to certain woods, we might have to cross private property and go through wooden fences that some owners had erected, but there was almost always a loose piece of fence "left unrepaired" to pass through (if not, then we climbed over the top). We were good Boy Scouts and always left things as good or better than we found them, and no one ever stopped us or threatened us.
Except other kids! In forests other groups of children sometimes might view us as hostile, perhaps to protect a "fort" (essentially a foxhole and a dirt pile) they had built out in the woods or who felt this was "their territory", and who might rain down clods of dirt upon us with little warning. We would parlay around it and if that didn't work, we were both pretty accurate with dirt clods ourselves and learned to keep moving so as to be difficult targets.
Today I get the impression most US-raised children are restricted to the house, the back yard (even the front yard is too dangerous) and adult-accompanied trips. So sad.