It’s not just the kids’ cell phones. It’s the 24 hour outrage and fear driven by the news and/or social media. So their parents won’t encourage them to wander off, and as others have mentioned the neighbors will call the cops on them if they do wander.

I live in a residential neighborhood. The main demographic that can afford to move in to the suburb is people already nearing retirement with grown up kids. My kids are constantly bored out of their heads outside because there's nothing to do, nowhere to go, and nobody to play with. We've hosted seven exchange students and the number one culture shock is the loss of independence that goes with moving into a car dependent suburb. Our city design, pretty much everywhere in the US, blows ass. We could be doing so many things so much better, and it would actually cost everyone, taxpayers included, less money. We are all literally paying orders of magnitude more to do the stupid shitty thing and pretending that it's great.