I'm sympathetic with arguments against a lot of the surveillance we see in schools, but it does a great disservice to the anti-surveillance position when you try to use an example where it correctly identifies genuine misconduct.
The girl in the article says that this sort of thing doesn't work, yet in the next sentence she admits that it actually did work, "I’m never going to do something like that again, because the repercussions I faced were horrible." The system correctly identified her and as a result she decided to not partake in such behavior in the future. This reads like a young kid who doesn't think her actions should have consequences.