TBH, I don't believe that to be true. Let's say you're a healthy 20-something that's been experiencing weakness in your hands. The doctor comes back and says

TBH, I don't believe that to be true. Let's say you're a healthy 20-something that's been experiencing weakness in your hands. The doctor comes back and says "This could be either arthritis (5% chance), cancer (0.1% chance), or nothing at all (94.9% chance). Test X will rule out cancer and test Y will rule out arthritis, but they both have a false negative rate of 15% and a false positive rate of 15%, and each test will cost $1,000 to perform". Now what do you do? I would make the claim that performing either test would be irrational given the probabilities. But people aren't going to screw around with their health. Your position also presumes that doctors know what the heck they're doing and can provide information to the patient that allows them to make an informed decision. This is meant as no disrespect to the profession at all, but the reality is medicine is a lot of guesswork. It's very normal for a doctor to prescribe a battery of tests, or trial medications, because all they can do is assemble hypotheses and then test them against the individual. I guarantee you, anyone with a chronic condition has heard something along the lines of: "Well, I don't know what that is, but let's try this drug and see if it helps". This is fundamentally why I don't believe healthcare can work as a free market. A free market presumes rational actors and perfect information, and healthcare is the antithesis of those things.