I'm not worried about the "privacy" of students at school--as has been pointed out, they don't have any. Their lockers can be searched at will, without cause or warrant, for example.
However I do worry about the effect this will have on the students later in life. Getting them used to this kind of thing in school is going to make them more likely to accept it in situations where it really is absolutely inappropriate. People already give up their privacy too easily, and this would severely exacerbate that problem.