I'm damed sure I'd be much worse at math if I'd not been pushed in a formal environment such as a school classroom. I liked math—especially calculus as it made sense to me—but parts became a drudgery when I could see no reason for studying them. Right, there's always the kid in class who excels at math like a mini Euler and gets bored because the rest can't keep up but the majority of us aren't like that—doing Bessel…
I agree with most of what you wrote, but this part is tricky. Yes, it would be nice to have math and physics textbooks synced. Maybe other subjects, too.
But writing a textbook is a lot of work; it can take years. How do we get two textbooks synced, if they are written by different people? One writes their book first, then the other has to match it? What if the other disagrees with how the first book was organized? They both write together? Now there is a risk that one does a good job, another does a bad job, and the good textbook is connected to the bad one.
Or maybe write the common outline first, and then each author is trying to follow it independently? Plus, there could be multiple versions of each book, following the same outline, so each math textbook can be connected with each physics textbook based on the same outline. Here the problem is that people often disagree on the outline.
Also, not sure how important is this part, having things in sync could slow down the improvement in the future. For example, imagine that we figure out a better way to teach something in physics. But now everyone is used to having math and physics textbooks synced, so the new physics books would be rejected, until someone rewrites the math books too.