[maphew]

What you say is true, our neighbourhood streets are more crowded and no longer suitable for kick the can and soccer and what have you, but I don't think it's the driving factor.*

It is a concern for safety, or at least usually couched that way, but what I hear voiced most often is fear of other humans. From older bullying kids, to hoodlums, to drugs, to predators. In short, Stranger Danger. The "don't talk to strangers" refrain I remember hearing occasionally when I was kid in the 70s didn't seem to have much effect. We just kind of shrugged. Looking around today, I see it took deep root.

((Oh yes, pun intended. It's a beautiful thing when they also perfectly express the thought.))