Why couldn't the school have prepared me for that when I was 16? Why does preparation take precisely 12 years and only then I can really learn anything.
Maybe you're right. You're taking your own anecdotes as evidence that schooling is useless. If schooling and university didn't teach you not to do that then maybe it's not all it's cracked up to be.
The curricula for school and early university semesters are largely standardized, which allows me to generalize my observations as all other students had to learn roughly the same in school and university.
What was taught in school over an entire semester usually was a single lecture in university. At least for the mathematics courses, where actually similar things were taught, just from drastically different perspectives.
If you're capable of university level mathematics then you're probably not the audience that school mathematics classes are most concerned about. It's unfortunate, but schools are trying to raise their average grades and your grades were likely to be good regardless.
Surely you had peers at school that found mathematics to be challenging, or even struggled?
Maybe the particular school you went to was terrible _for you_, but personally I learned a lot, both which helped me both at the (local equivalent) university I went after school and later in life.
Sure, I am guilty of being polarizing. But I honestly do believe that my 12 years of schooling were in large parts a waste of time and I would like it if people at least considered the possibility that you can have children do other things.
I am saying that school is terrible at teaching. If the goal of schooling is that students learn then the school system I was in was a total failure.
The moment I entered university I learned much more and much faster.