It's frustrating. Neither the hospital nor the insurer typically has sufficient information to give you an answer. It's even worse when your information like age or diagnosis history factors into it.
Somehow they can figure it out after the procedure. They could easily give you the cost for each billing code upfront but they choose to hide the information from the patient;
Last time I had a procedure done it took 9 months before a bill showed up. It's a many to many communication problem so they only bother to figure it out when they need to, and then it can take a while for the hospital and insurer to hash things out. I'm not saying 9 mos is typical, but I wouldn't wait anywhere near that long to get an answer on how long something will cost me. They just don't have the incentives to form all the necessary lines of communication among themselves prospectively.