Man Frankie is loving handicapped. They're not invading anyone's privacy, they have monitoring software on the computers they own. This is is no way similar to spying, I also really doubt they're recording anything. They probably have software setup looking for key phrases then report the account. Also a teacher can look at a person's screen so the kid can't close whatever it is they're doing when they see them walking over.
Privacy is a real problem but crying about stuff like this makes you a whiny crybaby. I also think it's pretty funny you thought this was "really illegal", like what at all made you think that?