(My mom is a retired CPS teacher.)
Shrug clearly teachers are paid more than the median wage. There isn't much to argue there.
Modeling wage/salary is pretty straightforward for the majority of jobs (weighted by number of people working the job). There really aren't too many surprises.
Monopoly/Oligopoly union power, licensing, labor supply, regulatory/compliance restrictions/barriers, and product/service output value are pretty much most of it?
No teacher is going to tell you they're not altruistic, and that they're in it for the money. They see themselves as doing good, and I agree that they are. But that's not what drives entrance into those fields.