>>10559468
I think it's all of them, actually. 100% must take a true emergency if they are classed as any kind of trauma center (some E.R.s are really fake urgent cares). Their payment comes from a state fund where I live, which is how they cover the costs.
The states also have medicaid for the truly indigent. You can arrive from Cuba yesterday in Florida and right away get your medicaid card, which is free healthcare and prescriptions. For the next tier up, there are the free county clinics for vaccinations and public health things like veneral diseases and some items, but you have to sign some forms that explain you can't actually pay, ie you have a low pay job. Then, for $30-80 or so out of pocket, you can visit any walk-in clinic or pharmacy with a nurse practitioner and get a script for an antibiotic, ear drops, cough pills, inhalers, or yeast pill, whatever little emergency it is.
Urgent care is the tricky middle ground where the uninsured and middle class underinsured might have trouble between general medicine and actual emergency. Falling from a ladder and being stable is E.R....but cutting your finger down to the bone is more like stitches at Urgent Care. Paying a co-pay is one thing, but paying 10-30% of a total hospital bill (adjusted) is heartbreaking and leads to people who don't get the care they should be seeking. People in the US with good insurance still should expect to out of pocket about 3-7k/year in preventative and routine costs.