Someone mentioned Stranger Danger... that whole movement backfired I think. Kids have a natural sense, similar to animals, of who can be trusted and who can't. Parents can encourage this "skill" but often they don't.
In the olden days parents just let kids run wild, which made them vulnerable to "stranger danger" and fortunately it doesn't happen as much as scare tactics would have you think... most people are okay... but it happens enough, and happening at all is bad, so kids need to be taught and encouraged how to be safe.
Flip this around, though... kids started being taught to be scared of all strangers because "you never know". It was an earlier version of man vs bear, frankly... teaching kids to just be scared of everyone because everyone was out to get them... but encouraging kids to always trust authority like police, even though police aren't all good... and oh, most kids are abducted or abused by someone they know... so turns out, being scared of strangers and encouraging complete trust in friends and families messes up a kid's natural defense intuitions and they run from all strangers, whether a threat or not, and trust all family, whether a threat or not.
Knee-jerk reactions never help anyone. Parents could just try being parents and teaching their kids to observe and be aware of their surroundings and to "read the tea leaves" so to speak. I know, for instance, I am horrible at reading people. I don't pick up on social cues at all. So I have to revert to just not trusting anyone be they friend or family stranger or known... because it's the only way to be sure. Because natural instincts weren't encouraged when I must have had them... and now I'm lost.
Fortunately, as far as I know, I've never been abducted or abused in that manner... but, it's more luck than anything else.
Some people really do love and teach their kids. Sometimes bad stuff still happens... but it could be way less bad stuff if parents and society did a better job.