What would be some impediments to getting an employer to experiment and take risks that might ultimately revise his expectations? One would be legislation requiring the employer to pay everyone the same wage. Another would be legislation making it costly to fire a lousy worker. After all, if the employer's hunch didn't work out, he would have to bear the costs of discrimination suits, and possibly costly settlements, to get rid of the employee.
A few readers, in response to my discrimination discussion, said that my argument justifies the racial segregation of the past. To explain phenomena is not the same as justifying phenomena. You could fall off the roof of a tall building. I explain that your death is a result of the forces of gravity that caused you to accelerate at 32 feet per second and the sudden deceleration when you hit the ground. Wouldn't it be silly if someone accused me of trying to justify gravity and your death?