 If patients and doctors were perfectly rational and motivated only by their own material welfare, and in the absence of regulation, there simply wouldn’t be a market for health services. Doctors would choose therapies that are best for them and not for patients, and patients would anticipate this behavior and stop seeking doctor’s services in the first place. In our world, neither patients nor doctors are particularly rational, nor are they motivated purely by self-interest, there are ethical codes such as the modern form of the Hippocratic Oath, and the health sector is one of the most regulated industries of all. All this does not, however, change the incentive structure in which doctors and other providers of health services operate. Because they and not the patients are experts, they have incentives to choose therapies that are in their best interests and not in the patients’ interests.