School are union based for teachers. All get the same, whether you are the best instructor in the school or basically incompetent but managed to get lucky and land a job.
There are many states including Iowa that are considering going to a merit based system for raises. Unions have lost there power a lot of places. In TX the state government is considering giving all teachers a $5k flat raise for next year. There is some opposition to that including those that want to give the money to the districts and let them divide it up based on teacher performance. As an educator (wife also an educator) a $10k family raise seems like a great deal to me though. My only vice with the merit based system in education is how they will grade each teacher, I just do not see a way to do it objectively.