There's a great post on reddit from a doctor who wrote about a typical patient-doctor interaction (which I'm too lazy to find right now):
Patient comes in with elevated blood pressure, about 30 lb overweight, sedentary lifestyle. Doctors talks about blood pressure, possible future issues with it, recommends patient start getting some exercise, portion control, lose some weight, maybe a dietary consult.
Patient comes in a month or three later for a follow up visit. No weight loss, no drop in blood pressure. Doctor writes a script.
Hell, when I was checking out doctor review sites for a podiatrist, one of the negative opinions he had said, "He didn't even prescribe me anything!