Well, "Yes Prime Minister" already figured it out. The whole education system is more for the welfare of bureaucracies and teachers/unions instead of students'. And that was some 40 years ago.
Education involves a lot of money. It's the interference of individuals that want some of that that deteriorates it.
They wouldn't need a union to collectively bargain if they were taken care of properly. On the flipside, I acknowledge that it is unfortunate that teaching seems to be a drip pan to collect people who do not succeed in primary careers, and that should probably stop also.
[0]: https://www.niche.com/blog/teacher-salaries-in-america/ [1]: https://www.calstrs.com/retirement-benefits
Please don't perpetuate this. Any half decent teacher is going to spend summer looking at curriculum, block/lesson planning, in meetings, organizing their classroom, doing continuing education and training, etc. Sure, it's not as much work and it's more flexible during the summer, but it's by no means time off. Also, they work a lot more than 40 hrs/week during the school year. Also, they have a lot less flexibility about when they get time off. Also (in secondary/postsecondary), they have exams immediately prior to Christmas. (And yes, I bet you get Christmas off too.) And so on.
But the unions ensure that the NOT half decent teachers get paid the same, and they’re taking all that time as vacation. With such an incentive structure, it shouldn’t surprise anyone that there are a lot of NOT half decent teachers, and they get a lot of time off.