Interestingly, Medicare is a slight counterexample to your comments, because you can -- given motivation to sit down and collate the necessary public data sources and understand the rules -- calculate what rate Medicare allows for a given procedure. And since providers who accept Medicare have agreed to those rates, it means that for Medicare, at least, you can find out the price (or the ceiling of the price, which is what people often want to know anyway).

Note that this doesn't mean the same procedure costs the same at every provider, though; Medicare rates include a geographic adjustment, among quite a few other factors, but it does mean you can work it all out for yourself.