Do they actually have different qualifications? Each of them has to be trained for a teaching job and, er, remember most of their school program?
In the same vein instructor at the bootcamp is someone who's good at motivational shouting and in all likelihood isn't missing opportunities to serve as a commando.
The fact that all teachers are trained the same is a big problem. Personally I am fan of not having "trained teachers" for anything beyond grade school
After that we should be using subject matter experts
No we should be using teachers, people trained to effectively communicate and teach concepts of a subject.
A subject matter expert can be an expert in a subject but terrible at communicating and teaching that concept. Knowing that concept is not equivalent to effective communication. This is analogous to Great Software engineers becoming mangers with no managing talent whatsoever.
Why would someone with a math background take $40k to teach a bunch of kids math when they can learn a bit of python and make $140k doing data science? Some do, but outside of rare exceptions, you aren't going to get the best talent.
You also end up with teachers who can't be bothered to learn how the subject is used in the real world. I barely put effort into learning matrices or complex numbers in high school.
"You just have to learn it, There aren't any practical uses for it" said my highschool algebra teacher told me when I asked what these are used for.