Answer: Because the reality is that the kids' educations and welfare are the very lowest priorities.
Idea: Colleges start giving admissions preference to kids from later-starting school districts, on the theory that those kids slept through fewer of their HS classes, and thus are better prepared for college. College-obsessed parents quickly deploy the torches, pitchforks, and whatever else it takes, to force school districts to make the "obvious" changes.
If even 1% of parents are overabusive to their children and justice isn't being served, that's 1 million parents. Justice systems aren't set up to deal with this sudden influx of criminals so they ignore it..
Idea: Colleges start giving admissions preference to kids from later-starting school districts, on the theory that those kids slept through fewer of their HS classes, and thus are better prepared for college. College-obsessed parents quickly deploy the torches, pitchforks, and whatever else it takes, to force school districts to make the "obvious" changes.