(Public) High school is for the politician's benefit. Public education was first and foremost a way to assimilate immigrant groups so that they would adopt a uniform culture; second a way to provide day care so the parents could work at the factories; third a way to get students used to factory work like following directions and showing up on a schedule; and only last a way to provide valuable skills and education to the student.
You can see that by observing the conditions under which a state is willing to not have students go to school. If the schools are not teaching the ideology that the state wants, their funding gets axed entirely; you can see that with current MAGA efforts to defund the DoE and various public schools, with the DEI efforts in California, and with the anti-DEI efforts in Texas and much of the South. Likewise, if the students are being subversive and talking about getting rid of the capitalist system entirely, you shut down their schools and arrest them. If the adults no longer need to go to work, you see states entertain the possibility of students no longer going to school; you saw that in COVID. But if the students aren't actually learning anything, as is the case in much of the U.S, it's not a big deal.
Education that is actually for the student's benefit rather than the teacher's usually tends to be private schools or tutors, or occasionally charter/magnet schools. In rare cases, you'll have a public school where the surrounding community really values education. But notably, attendance is not mandatory in most of these scenarios.