Many people are not aware but it makes a BIG difference what radeologist you go to. The radeologist is the person who distinguises between a normal and abnormal growths. This is the specialist that can spot a tumor in a haystack! So you are paying for skills just like you pay for a surgeon, and no less important.
In new york I haven't seen 1500 radeologists unless I go to some rich-people places. I pay about 400 bucks for my brain mris. Fortunately the insurance covers most of it. The price is for the doctor, the machine time (hey its an expensive machine), operator time, etc. Though some machines work much faster than others. (a 5-10 minute procedure vs a 30-50 minute one).
And don't forget, lots of the great prices of lawyers suing doctors for everything are passed right on to you. And the fact that some americans are uninsured and have to be treated at hospitals means that those who are paying get to be charged extra to offset the problem.
So yea a universal health care system would benefit everyone and drive down prices.