Agreed, it's rare, but does happen:

http://www.cbc.ca/news/canada/british-columbia/child-s-disap...

This person is also accused, not found guilty (from the link, and no quick Google turning up a conviction).

It does very rarely happen. But even of the subset of events that aren't totally fabricated, many turn out to be more innocent than they are made out to be.

People getting their worldview from these sources are going to be unnecessarily worrisome about such things, which is really the point of the grandparent.

I dismiss all of these cases out of hand as fantasy, because the chances of this actually happening to me are as close to fantasy as being eaten by a shark while I am struck by lightning.