Emergency rooms are required to try and stabilize patients before they discharge them. These patients are billed after they leave the hospital, insured or not.
If I try to schedule a checkup or procedure, I need to give my insurance card first. Uninsured can pay for a flat fee upfront. If they can’t pay, they get no service.
With insurance, things get complicated. The facility will try to give you an estimated cost of the service. But it’s always a back and forth with 2 or 3 parties; the insurance, facility, and doctor network. If there is a disagreement between parties, you the patient get a bigger bill. Even when you payed for the procedure beforehand.