You’re missing the point. No, it is not a Zone. No one is stuck there. The mother made a choice and most likely signed a contract. She has a choice to follow the rules or leave.
Parents choose these schools because of the military type atmosphere. Note the word “choose”.
I think the problem is the little boy's haircut frightens the girls ~ and right there is the biggest problem in America when it comes to schools ~ they are not separately organized by sex.