I thought the conundrum goes like this.
A good techer is generally one that can teach year after year. Meaning, that the school is set in that Mrs. X teaches fifth grade and we do not need to even think of who would replace her. As well as her teaching methods are not stuck in a certain time period.
Therefore, teachers pay starts of small. Because they do not want to incentive teaching as a year by year career. It is better if there is growth by staying in one school.
Also, unqualified teachers will not be able to try it just for the money.
Schools have the ability to not raise the teachers after a certain point, because they would have to start over in different school at a lower pay. Though I have been told that this is an exception.
But this is old hoc.
I hear that the problem now is just a shortage of interested teachers. Every business is short on good candidates, and education is no different.