Don't most schools close for the day at 3pm nowadays? That's ample time to get home.
Remember there are no end of out-of-school activities, after-school clubs and whatever else so it's not completely unique that little Timmy finishes school at 3pm and goes straight home. It was tooted (and it comes up semi regularly) to extend the school day so it more closely matches working hours, ie 5pm finishes under the guise of helping working parents. Teachers didn't really appreciate that since they already work after 3pm for lesson preparing, marking and whatever else.
Of course its ironic when you consider little Timmy and friends already have more time "off" in a school year than any working adult in the country is legally entitled to anyway but I digress.