Then you are truly clueless as to how common rape and sexual abuse have become in the public Skrules. A better option is to monitor what is on your child's phone.
Cameras available at all times are an outstanding idea for parent's who don't care enough about their children to send them to private school, or home school.
I support litigation to shut down any public school which has so much to hide that it tries to ban camera phones.
Camera phones, so far as I know, are banned from all standardized testing because students can use them to take pictures of the test and distribute them. Phones in general are banned because of the possibility of students texting friends to obtain answers.
One of my children is still in college, and the professors there have very strict policies banning cell phones in class.
In high school, texting is a lot more fun than old fashioned paper note-passing. Your friend doesn't even have to be in the same classroom with you...plus you can send messages to have your friend meet you in the bathroom, etc. If caught, 9 out of 10 students will say the conversation was "with my mother."
By the way, I've attended a couple of seminars on school security post-Columbine, and all of the security experts have said that after a disaster they expect cell phones to be useless because all the students and parents trying to contact each other would jam the circuits, so school officials should have one unlisted landline to contact authorities in such an event.