I wrote Hacking Healthcare, created clearhealth open source EMR, a decade plus managing hospitals and multi-practice groups. There are a couple of bad actors out there but for many of these organizations, though it may seem impossible to believe, they really haven't yet been able to coordinate all the entities involved to put together the list. People think of hospitals as monolithic entities but many are much more like medical malls than anything.

Further for many institutions there is a plain cost/benefit. The maximum penalty for non-compliance is $109,500 a year though as far as I know 0 fines have been assessed yet. If you are a large institution it can easily cost many times that to put together and maintain this list in a compliant manner.

Byzantine barely begins to describe the way medical procedures are billed, inpatient especially. It is not at all like a retail interaction. For a given patient on a given insurance program on a given period within a contractual cycle, the rate of charge and reimbursement may differ. Many contracts include a most-favored-nation type clause that mean when one program's reimbursements change then many other ones may need to be updated as well.

I'm not trying to defend any of this but just point out that there is a lot of behind the scenes complexity to the current system that is easy to gloss over when it is thought of in retail terms.