I keep hearing that as a reason suburban kids don't leave their yards but I've been walking those neighborhoods for decades now and have never seen anything or anybody that could be construed as dangerous to children.
I grew up in a bit of an urban jungle yet was outdoors pretty much every daylight hour during the summer, riding my bike, playing pickup ball, and just generally hanging out with my peers with no parents around and getting into the typical juvenile (minor) mischief. And yes, I did get picked on or even beat up from time to time from the bigger kids.
I don't thinking walling children off in their backyards is very healthy. When they grow up, they tend to be super-sensitive, easily rattled and in the case of boys, very weak and effeminate (at least by the standards in which I grew up back in the 1970s).
During the school year, as I take my walk around the neighborhood, I see most parents driving their kids to the bus stop - sometimes even to the end of their driveways. The kid doesn't leave the car until the school bus is stopped. Then when the school bus returns, the parents are right back there waiting for the bus to pick them up. I'm not talking first graders either. These are kids probably in sixth or seventh grade.
Air Conditioning.
We are all so used to being inside at 75 degrees and isolated from the outdoors and the heat.
Back when I was a child few had A/C and to escape the heat and stuffiness of the house we’d all spend time outside on the porch or in the shade.
So a person could actually hear the ice cream man coming.
I agree with everything you said. The perception of danger is far worse than the danger itself. I walk my dogs twice a day in my neighborhood and work often in my front yard and have never seen anything that was a threat to kids - except drivers driving too fast on our street. I never see children playing in the street on in front yards here as I did when I was a child. No kids walk to school by themselves. Ever.
It’s a different world now, very different.