While it's certainly been the exception and not the rule, I did experience personally a situation where I took a friend of mine to the ER due to severe abdominal pain, and she got the 'give me your insurance information' before she was triaged. This girl was in the waiting room on her hands and knees, rocking and vomiting, and there was a young girl behind the glass demanding the information. I was infuriated, and told her she better get someone out there to get Mindee back to be seen immediately. We wound up just giving her the card and going on back. My friend was seriously ill with a bowel obstruction and needed surgery during the night. While she wasn't imminently dying, she was severely sick and could've had major complications it her care was further delayed. It was a horrible experience, and one I hope to never go through again. Fortunately for her she had no complications.
Now, at the hospital we mainly use here, there is a triage area just as you enter the doors of the ER, so that folks are seen and triaged before anything else takes place. If you don't need emergent care, then you are asked to complete your registration before being sent back to an exam room. Now, keep in mind that this is for walk-ins. Someone coming in by ambulance goes straight to the exam area, and as someone mentioned a family member or other loved one usually fills out paperwork.
I happen to think that regardless of universal coverage, people will continue to use the ER as a walk-in clinic, because of the relative convenience of it. I would bet that a large number of folks using the ER for this reason do so in the evenings, either after they get off work or due to fear that the doctors office isn't open in the middle of the night. I also don't think people will take advantage of the 'preventative care' benefits as much as TPTB suggest. Hell, I've got preventative coverage for me & my family, and I don't get a yearly comprehensive exam, nor does my family.
No system is perfect (despite what Dean tries to tell us

). But... no one is 'shown the door' at an ER for inability to pay, and we do have IMO the best medical care available in the world. IDK what the answer is to all this, I just happen to think
this isn't it.