YSK: Medical Debt cannot be sent to collections
Collections agencies need to provide you with an itemized list of what you owe and to who. If a hospital gives out this information, especially if they didn’t even try to collect it themselves, they have violated HIPPA. Will a collections agency give you a document proving they vioated HIPPA? No. Do you owe debts on something w/o receipts? No.
Where are you going where you aren't required to sign a financial disclosure allowing for the relevant information to be sent to whatever service is used to collect payment? I haven't been to a single doctor's office, urgent care, or hospital in several years that didn't require me signing a form consenting to that.
Collections also doesn't need to provide an itemized list of every detail you owe for, not in the way you're implying at least. They're not about to say "you owe the hospital $20 for an aspirin." They can, however, say "you owe [this hospital] [this dollar amount] for services on [this date]." The itemization they're required to give is the current debt, any fees and interest, and any payments or credits made on it. That's straight from CFPB.
In nearly all cases, debt collectors are legally required to provide you with certain information about the debt when or soon after they contact you.
Zuberi