Do we know why these kids were convicted? Was it for petty stuff like you mention or was it for worse crimes? (I'm sure it was a mix; 4,000 kids... damn.)

And, regardless of their (possibly not even real) crimes, we can't be certain that they would have been convicted if the judges' profit motive hadn't been there.

I agree that the police are involved in ridiculous ways when kids misbehave at school, but I don't think it's fair to assume that all of these kids would still have had their lives ruined if it wasn't for some corrupt judges.