Not kids, parents are scared, kids have no say unless they are already addicted to gaming, tv or whatever their latest addiction is, and then they themselves don't want to go and just sit and consume.

Even if the chance something actually happens is terribly low it became unacceptable. Death of any type became unacceptable, so got injuries, bullying is end of the world. Maybe due to having 1-2 kids instead of 10 and seeing occasionally other kids around die from whatever, so what was sort of normalized is shocking now.

Parenting got much, much harder, expectation of what a good parent is are stratospheric compared to - kid didn't die, you didn't beat him up (too much), didn't rape him and similar level. The more you invest yourself into any activity including parenting the the less you can ignore or accept failure of any sort. And so on.

I grew up free as a bird too, had a small bicycle and roamed fields and city too, but cars were few and slow ones. Its still possible but even for my kids it has to be outside of roads, luckily we live now next to forest and vineyards with roads closed to regular traffic. So it seems its whole societal change of mindset, not limited to US (although there I believe its the worst due to everything car-centric, few continuous pedestrian walks etc)