Also on the teaching angle, I think the fact that as you get higher in math, the more variety of ways it can be taught start to plague most people, as well. You'll have a teacher one year that tells you to solve equations one way and another teacher the next that will want to you to solve it another way, even sometimes going as far as punishing students if the problem isn't solved the way the teacher prefers, even if the answer is correct.

Most schools in general have a problem with teaching any subject where the teacher's ego will often get in the way of actually having students learn material. I had a teacher in early elementary school that would literally rip your assignment up if you didn't have your book on the left of your desk, and the piece of paper you were using for work on the right. Now that I think about it this could have been her way of discriminating against left handed people (yes, that is a thing) without saying it so she could pass it off as a different reason. Either way, that's an example of the BS that can happen in ALL types of schools. Everyone's human, no matter if they teach in the ghetto or in the best school in the country.

Anyway, going back to math now, I also agree with how you have to know more and more math as you get higher in education. If you don't know some material or are just plain bad at one or two aspects of math, you more or less have zero chance at whatever current level you are at which in turn doesn't properly prepare you for the next level.