You don't have to pay them unless they're specific. I got a bill 3 years after being in an accident and I asked them for the documentation they legally have to provide me (itemization, the legal basis, detailed incident record, attempts on their part to contact insurance) of how they arrived at the sum. It's been a year since and they haven't given me anything. Besides this kind of billing is banned in California now…
I think I’m realizing that what I cherish about the healthcare system up here is not just that I don’t pay bills, but that I don’t even see a bill. Not that the bankruptcy inducing costs aren’t wretched, but I just cannot even imagine being put into a fucked up bureaucratic hell while my family is in a life altering crisis.