If everyone had perfect knowledge of all prices offered by all healthcare providers and all such services could be purchased with pretty high levels of efficiency, it wouldn't provide universal access to health care.

By itself, no. It's just one of a thousand moving parts that should be optimized. When we talk about one thing (like transparency), I don't think any serious person would consider it a silver bullet that solves the whole mess. We're talking about one thing in isolation. We still have to talk about the other 999 moving parts, too.

A quick example. There are two BIG imaging companies in Arizona. One is SimonMed, the other is Banner Imaging. There are more, but I only need two for my illustration. If I need an MRI, which is cheaper? They both have 4T MRI machines, and competent people. I want to go to the cheaper one. If you call them, they will tell you that until they submit a claim (or pre-auth) they can't answer that question. And you can't really go by their cash price (if they even have one...many do not) because different insurances will have negotiated different rates.

That's about as opaque as it gets.

And then, to make matters worse, I scout out which one is on my insurance, I go there, and then I get an EOB indicating that the procedure isn't covered because the name the facility used for the claim isn't an in-network provider. Even though the facility is. (I'm actually fighting that battle right now.)