But that is true with "private" insurance as well. My Explanation of Benefits show the "full price", the discount price my carrier has negotiated, the amount they will pay and what I must pay.

The difference and there is always a difference - is "lost" as you say.

When I see my PCP doctor my copay is a percent of what the insurance covers. As the doctor does not know how much this is...I pay nothing at the time. My doctor send the bill to the insurance company - they decide what they will pay - send that back to my doctor and them he must send me a bill for my percent of the bill.

I have tried to pay something at the doctor's office but it cannot be done that way. I must wait...and so must my doctor!