And if you think that's bad try getting a Computer Science teacher to literally shave six figures off their salary!
I hate to bad-mouth teachers, because there are so many people taking haircuts on their salary for altruistic reasons.
But my experience tutoring college math majors is exactly this. The low performers are nearly all interested in teaching, the high performers nearly all headed to either grad school or engineering/finance.
That's why you'll encounter a lot of super great humanities teachers but a lot fewer stellar STEM teachers.
Salaries are unequal, so that naturally reduces the prestige of being a teacher. It's also a traditional "feminine" job with strong parenting/caregiving elements that further chips away at its status for some.
I don't judge anyone for seeing teaching as a "plan B"; however, the significant turn over/drop out rate of teachers would call into doubt whether it is as safe + easy a back up career as we culturally project.
I don't know if this is true - but that math major is probably a lot more likely to go work for an accounting firm at 60k a year rather than put up with the stress of teaching at 40k.
Finally, I actually agree with you on the pay vs. proof of outcomes thing. The problem is that we lack reliable ways for measuring teacher efficacy. I have worked in both urban and suburban schools. I'm not a better teacher in the suburbs, but I sure as hell look a lot more effective.