I have a friend who had to have an emergency appendectomy this year. She paid $1500 for it after insurance. My father had knee surgery he says they tried to charge the insurance company $64k for it.
At this point I think the pricing is all arbitrary. It’s about them trying to charge what they think they can get away with and sticking you for the rest. Kind of like raising the price so you can offer a deep discount later on. I think the real price of the surgery (without insurance) was probably the $7.5k.
I can think of no other business where you agree to have work done without an agreed upon price. The insurance company will tell you it’s covered but the hospital you go to may decide to play games with you. At the very least I suppose they are just hopping you pay so they can collect interest on your money on it before sending it back.