E.g., I had my vocal cords looked at; took only ~1/2 hour of an ENTs time, and is a (somewhat) common and non-risky procedure. $4,000. I have no way to justify that price — I highly doubt the ENT is making $8k/hr! It was one of the big reasons that drove me away from PPOs in general: completely opaque, expensive, retroactive billing. Going to the doctors puts you on the hook for near unlimited liability.
Now, Kaiser was a nice contrast; I had the opportunity to get my wrist operated on for RSI. Somewhat invasive, would require weeks of healing, not guaranteed to be successful (it had a ~50% success rate!): $300, priced out before the operation.
(Sadly, I'm no longer with Kaiser, as they were west-coast and the rent was too high.)