>Public school system does not have such luxury

This is a very important point. Private schools can simple expell troublesome students. At the public school one of my kids goes to, there's a 10 year old who sometimes gets very agressive and lunges at teachers, punching and kicking. The teachers are female, and not much bigger than him. The school is the only one in this district (small town), they can't send him to another town unless transportation is provided for. If it was a private school, he would have been expelled on the first or second episode.