Twenty years ago was still a very different time in this regard. (Anecdotally, I notice that people who are in their mid-twenties and older have childhood memories very different from what is considered acceptable nowadays, both informally and legally.)

But why? I thought crime rates in America had actually declined significantly since 20-25 years ago. If so, then why would it be more unacceptable today to let children play free than it was twenty years ago; has irrational helicopter parenting grown for other reasons, e.g. status competitions, with no correlation to actual danger levels? (Or is there something subtle I am missing, for example has violence declined in ghettos/low-class areas but the middle and upper areas we are talking about are less safe?)