I don't get to choose the classes I teach. Some years I get high ability groups, other years I don't (We group by ability in the UK). Who does the judgeing and who sets the standards? Not only does merit come into it. What about expertise? In the UK we have Phys Ed teachers coming out of the woodwork but can't get physicists for love nor money. We have a standard pay scale so everyone gets paid on the same scale according to length of service. Should a Physics teacher get paid more because they are rare?