Doctors & Patients: What Makes an Expert?

It occurred to me a long time ago that our expectations of experts can be quite peculiar, and the doctor - patient relationship provides a good example.We usually go to the doctor with our symptoms which can be wide ranging if we are seeing a general practitioner. From the common cold to some rare and unidentifiable rash, we allow ourselves to be examined, poked and prodded as needed to allow the doctor to make a diagnosis. Which he or she duly does from past experiences or, when it gets too tough, is sent to specialists who continue the rounds of tests until something (hopefully) works.
The point that I noted with interest was that it is rare for any of these experts to have actually experienced the symptoms or suffered the pain and discomfort themselves. I know that it is just as well we have some "independence" in the process but surely we lose something when all that is provided is a second-hand experience and book learning.
This is an argument that applies equally to "consultants" of all colour and hue. I'm thinking here of some of the most respected roles in our community - besides medico, the same can be said of lawyers and priests. And while I think there is an argument that can be developed each way, there definitely IS an argument each way.
The real mystery is why we think it is normal to ONLY have people with book-learning and second-hand experience diagnosing and advising on a range of societies critical issues. The lack of "real-world" experiences in our experts is what makes for classic jokes like the definition of a consultant, as someone who borrows your watch to tell you the time.