Why do doctors have to Treat all patients fairly and without prejudice?

It is a bit odd to have to explain why fairness and lack of prejudice are better than unfairness and discrimination. However, the medical profession is special. People have to be able to trust doctors because people are very vulnerable to medical abuse. Doctors can do pretty much anything to their patients, they give them drugs to take, they perform surgery, they have complete access to their patients' bodies. In order for them to deserve the trust of their patients, they must adhere to a very high ethical standard and not abuse anyone's trust. Naturally this includes treating all patients fairly and without prejudice.