I’m pretty sure that sort of thing has happened at the schools I’ve worked at (as laowai, I get a free ride on most hassles of that nature ), but what’s more frequent is one relative (e.g., grandma) picking up the kid and the other (usually the mother) showing up later and saying, “Where’s my kid?”
That doesn’t sound like a problem, but what sometimes happens is (a) nobody remembers the kid being picked up, (b) whoever was watching the kids when that one was picked up has gone home, or © whoever, etc., is out of pocket at the moment.
That’s when people start getting scared.
Another thing is kids coming and going on their own. One night a long time ago at my school, I went out to satisfy my nicotine urge, and as I was walking back from my smoking station, I saw two of our students (older sister and younger brother, like maybe nine and seven) leaving the school. Also, I could have sworn I knew who they were. I went upstairs and asked some teachers if those two usually walked home, and they said no. Nobody got very worried, though because everybody at the school thinks I’m nuts
Anyway, the next day, those two kids swore up and down that they didn’t walk home, that their mom got them, etc. I don’t think I was hallucinating, but who knows?
Anyway, no offense, Durins Bane, but I’m not sure I’d want to be in your position. . . .