Just job security I suppose. That and if they tire themselves out during the night, they are not likely to have a full tank of mischief during the daytime when the justices and other enlightened public are at risk.
In Duval county if your child is truant, the parent gets arrested. I don't see how anyone can say this practice does not teach kids that they are 'not' responsible for their actions.
Kids shouldn't have a curfew so they expend their extra energy being out late at night and have to sleep in and miss school so their parents can be arrested./sarcasm>