50 stranger abductions in a year? You're off by a factor of close to 1,000.
58,200 non-family abductions in 1999. Of those, most were someone known to the child, but 37%, or more than 20,000 were stranger abductions. 75% were by males, 25% by females.
Evidence not that we shouldn't be wary of either sex, but that we should be wary of unknown adults of both sexes around children. And because more men than women are perpetrators, by a large margin, it's understandable that people are more wary of strange men than strange women.
I agree with the point of the OP. It is more difficult to be male as regards this issue than it is to be female. It sucks that people are suspicious of men trying to protect their children or sell them insurance. I understand and agree with that. Further, as I said, when I see a person I don't know, of either sex, on our complex playground around the kids, I'll approach that person regardless of sex. It's harmless, and if that person has reason to be there, they have nothing to fear and no reason to be offended.
I agree that it's foolish to automatically trust all women and distrust all men. But given the disproportionate number of men who commit these crimes, I understand distrusting strange men more than strange women around children.
Also, I don't grant any stranger my trust. Trust must be earned, not given out freely.