Where are the best in class teachers?

Are they hiding among the teachers in general? If they can't be identified, there is no effective & material differentiation (read: no justification for higher compensation) among them vs the less skilled.

Are you saying that the best teachers, in principle, could be measured, but we haven't developed the methods to do so (to be sure, a real possibility)? Or are they simply 'better' a-priori/intrinsically regardless if we can measure it or not?

The best in class athletes to best in class teachers comparison either fails or finds athletes winning flat out.