Do you happen to know how one would be billed for this if they didn't have insurance?
To be clear, it's not like the hospital won't attempt to collect payment from them; they will. And some are downright assholes about it and will resort to scare tactics (usually farming the work out to a 3rd party). But, to maintain their tax breaks as a non-profit, etc. they are required to work with - and even forgive - patients who cannot pay.
Note: some hospitals are also assholes with the services they provide. They can't let someone die because they can't pay, but once "stable", then can boot you out.
Below this point is possible misinformation. It's my current understanding, but if someone with more direct knowledge can weigh in, I'd be very appreciative.
The above is where a large chunk of the costs for everyone else comes from. Basically, those who can pay are expected to pay for those who can't.
Where it really hurts is for those people who are - what I'll call - barely middle class. They probably make ~$50k / year and if they have health insurance, it's probably not a great plan: very high deductible and/or max out of pocket. Since they are insured, they will get a much higher bill (initially sent to the insurance company) designed to compensate for everyone else who is getting cheap/free treatment. And, because they insured, legally the hospital doesn't have to reduce the cost or forgive the debt.