It wasn’t on Facebook
I wasn’t clear, sorry. I meant “Facebook” as a shorthand for the totality of stuff that is on the web and which people post on the web (in various forums).
The point is just what you said: given info that is available on line, including that posted thoughtlessly by teens, it’s pretty easy to be tracked down by a predator.
And, while kids may not post track schedules on Facebook, they most definitely post things such as “c u at track tonite” and “r u going to be at track tomorrow?” You’d be surprised at the amount of substantive info is passed in what at first appears as dumb chatter.