Cost accounting consists of more than just balancing a chequebook to the penny; you need to attribute expenses to specific procedures, which can get a bit tricky. It requires discipline and cooperation throughout the organization, which would likely be a huge change for hospitals (as I'm certain doctors would be loathe to log their time like lawyers do).
OK, so if my company knows how much it's spending on toilet paper for the washroom, but doesn't know exactly which departments are wiping how much ass, then we are not doing cost accounting though we are tracking the bulk expense properly in the ledger. We are not able to answer the question of how much toilet paper is required to operate our marketing department, for instance.
Widely used supplies like that are usually just put into a general overhead account, sometimes specific to a department.
Healthcare companies would need to attribute things like depreciation of equipment (MRIs & CAT scanners for example), as well as doctor and nurse time (outside of operating rooms). These things are generally not tracked accurately, and many professionals are indignant at the idea that they could be.
If you're doing accounting you have a ledger which balances down to the penny, and the expenses are spelled out in there with concrete amounts.
This is why that judge, as noted in the article, rejected the argument that the cost of an X-ray can be unknowable.