(4) buyers capable of making informed decisions (a) several nearby hospitals (b) enough expertise or impartial advice (c) not in an emergency situation, in pain, unconscious, intoxicated or otherwise unable to make good decisions (d) in a position where the price matters - not too poor, not too rich.
Since much of the above is not true in real life, a patient centered market for Healthcare does not work well.
The overwhelming majority of healthcare dollars are not spent in emergency situations. If you decide to go to the doctor because of some pain in your neck that's not an emergency decision. If the doctor tells you to get tests that's not an emergency decision, etc, etc.
You can go from healthy to cancer to treatment to more cancer (wash rinse repeat until you or the cancer is dead) without a single decision made under any meaningful time pressure.
And the guy who goes to the ER with a serious heart problem gets admitted and leaves bankrupt? Seems important to avoid that. Even for the cancer - you're in the most stressful situation of your life, you want to evaluate prices? What about your vulnerable grampa?
In the UK, where I'm originally from, I've never met anyone who wishes they had a role in evaluating healthcare pricing. In the US, I personally don't either.
Since much of the above is not true in real life, a patient centered market for Healthcare does not work well.