My wife has experience of the doctor's office asking insurance company for $X, and the insurance company comes back and say "no, max $Y". So then the final "cost" all of a sudden becomes $Y. Pay attention to the claims that your doctors send to insurance company and you might be able to see that.
So instead of telling you, yes, whatever procedure is definitely just going to cost $Y. They can't tell you how much things are. It depends on maneuvers with other players in the industry.
This is very different than say in Canada. If I want to get a teeth filling in Canada, my dentist straight up tells me how much before the procedure. If I want to price shop that, I can. In the US, nobody is willing to say how much, because "it depends".
It's not because intrinsically there can't be price transparency. It's because of all the messed up incentives that the industry has that causes US health care to be as such.