By the same hand on the employer side. If the doctor employee is good then you want to keep them if they are the only good doctor in town. Even if they're not great if they are consistent you want to reward them because the replacement would have to be convincing someone out of town to move. But if you live in a large city with tens or hundreds of possible doctors you know your doctors will likely be poached but there are also more where they came from so why bother rewarding loyalty when you don't need to be loyal to your employees?