hehe, a chance to put on my public health cap.
It is also important to remember that a physician is (predominantly) trained to address an individual patient, mostly pertaining to the specific ailments or concerns of a patient presented to them at the time of their visit. If they happen to have expertise in wider concerns -- like preventing those situations arising in the first place, preventing society-wide outbreaks of those conditions, access to health care, health care financing, running a healthcare organization, or public policy related to healthcare -- those are all bonus competencies that are not assumed in the basic quality of being 'a doctor.' Your favorite doctor may well be very good at what they do, but what they do is not all of healthcare.