Another aspect is, as we've grown more isolated, we've stopped trusting strangers.  In most cases, this distrust is entirely unfounded.  But no one talks to strangers, so who would know?

A confident child is actually at much lower risk than a timid one.  Timidity is a vulnerability, and predators prey on the vulnerable.

Most kids in most places would, I think, be safe if they're with one or two siblings or friends, and if they know how and when to approach adults to ask for help.