For a hospital, your care is not merely the interventional aspect of medicine, but also the vitals, diagnosis, charting, and time spent on reading your documentation by a medical professional with > 20,000 hours experience & training.
I have never in my life experienced an ER doing anything competent that remotely resembles reading documentation as part of triage. Why on Earth should they get paid more than a tiny nominal fee for the use of the waiting room and a bit of time spent by the triage staff?
"Terell's cousin is handy and while he's not the greatest he can probably get 'r done for more time and frustration but a lot less overall expense" is the nuclear option that caps how big a bag of dicks a shop can be.
Barrier to entry is low and they don't have an AMA cartel lobbying the government to protect them which helps a lot too.
Because you're a regular.
If you're not a regular customer of theirs expect a diagnosis fee that's about equivalent to half an hour of labor.
They also won't charge you a diagnostic fee if they know ahead of time that it is a service they won't provide like in the example. If I somehow end up at the tire shop for an AC service, they don't send me a bill 6 months later for an arbitrary amount just because they had to tell me that I need to go to the shop down the road for my issue.
I don't live in the states anymore, but I genuinely don't understand how any of this is legal. If I started sending out invoices to every client months later for services that they didn't know they were getting, with arbitrary prices, sometimes with egregious errors on them, I would expect a knock on the door from the authorities.