If the main purpose of education is to teach things, then that requires considerable skill on the part of the educator.
If the main purpose of education is to place hurdles in front of students so that those who clear them can signal (in an imperfect-information game) that they possess the ability to jump over hurdles (perhaps through high self-qi), then that is less difficult for the educator: a large variety of hurdles are equally effective at this kind of signaling.
Hypothesize that the wages earned by educators reflects the skill required or not required, and therefore their purpose in the education system. That is, we can "read off" an educator's purpose (teaching or setting hurdles) simply by looking at their salary.
Counterarguments:
Teaching useful basic skills is easy because of the simpleness of the skill and people's innate (perhaps self-motivated) ability to learn, and because of this, educators of basic skills have low salaries. Primary school teachers earning very little would be an instance of this counterexample. Meanwhile, setting hurdles is difficult because there needs to be considerable infrastructure to prevent students from cheating.
Business school professors typically have high salaries (I think) among educators, but the observation that all they do is enable signaling in an imperfect information game uncontroversially won a Nobel Prize (2001).
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