And what kind of metrics can you use to determine whether someone teaches well? Whatever metrics you use, there's probably ways to game the system without providing better services.

Exactly, and this would be just as true, only on bigger scale, if we just raised wages and tried to filter out 'the best of the best' from a now larger pool of candidates. I should write "if anything" at the start of my previous comment as I don't really believe a good solution based solely on financial incentives exists.

Your other comment efficiently expresses my intuition on the topic.