Why don't doctors have "performance/incentive based pay"? Exactly the same problem as with teachers. Which doctor will want to treat incurable diseases in patients if they are only paid when a patient is cured? Doctors would only be treating patients with diseases that they were absolutely sure they could cure.
Likewise, which politician would like "performance/incentive based pay" as voted by the community? If political decisions were only paid on value as perceived by the community, how many people would want to be politicians?
The business model does not work for a number of different professions. It's flaw is that it assumes a factory assembly line where all things can be measured equally. It is a wrong assumption but favoured by conservatives who value money over people in their economic rationalist worldview.
Merit Pay for Teachers: A Poor Prescription for Reform
|Harvard Educational Review|