Meno, that statement was meant to prove that it is hard to get a teaching job and therefore, generally speaking, someone would have to be a good teacher in order to obtain and keep his job.
Therefore, your comment had nothing to do with my point.
But in any case, I’m not sure that I see the logic in your point. According to that logic, any job that involves a lot of competition shoulc be low-paying. According to that logic, Hollywood actors should be underpaid.
I think the reasons that teachers get paid less than Hollywood actors have to do with other factors.