They do. It's called lunch detention. This girl's beef is that she got sent to lunch detention for causing trouble in the lunchroom by not following rules.
Understood. However, my comment had to do with establishing a fair policy rather than a over reacting to a large number of kids and imagined problems of the school. An out of hand lunch room is a result of poor supervision and discipline.
Children need discipline, but not an environment in which they are practically tied down every minute of the day.