Let's apply this to bankers, too. They must give a checking account to anybody who shows up, and their pay can be based on how much money is in those checking accounts at the end of the fiscal year.
a teacher's job is to teach their students. a "banker" (at the sort of bank where you might open a checking account) isn't expected to grow your checking account for you. you're supposed to do that, and the bank is supposed to hold it safely. I don't understand the comparison you are trying to make.