That was a fun read, but no one can teach that way. You can't become a teacher by studying math, physics, chemistry, biology, literature, french, programming, history, geography or english. You become a teacher in the US by getting a teaching degree. I believe that is the biggest problem we have in the US education system.
Teachers only need minimal knowledge of their subject, and if someone discovers that they don't actually like teaching then they just keep doing it anyway because they got a teaching degree, and can't do much else with it.
I know a number of math teachers who have undergraduate degrees in math, and then attended a 2 year masters program to get their degree in teaching.
I also know a number who came from a humanities background, and "learned enough math" in the single, poorly taught math-for-teaching class they had in getting a masters.
One of these groups makes better teachers (and likely has a wider career path, because of the undergraduate degree).
I also know some smart teachers that started with something else and ended up teaching high school. I have more examples of people who got a degree in something else and wanted to teach, but then found out how hard and expensive that transition is.
Low standards for math teachers is a huge concern, and Lockhart addresses it too, I believe.
Some possible ways to help: give teachers less class time and more time to prepare interesting lessons, pay teachers more, raise the standards of training and hiring.
Teachers only need minimal knowledge of their subject, and if someone discovers that they don't actually like teaching then they just keep doing it anyway because they got a teaching degree, and can't do much else with it.