Re: So...
I'm in the Midwest. A couple of years ago I temporarily lost the sight in one eye while playing with my toddler - most disconcerting. I was rushed to hospital with the ambulance tech doing little more than keep talking to me for the hour long journey (I live in the middle of nowhere). I got a bill for $8,400 (along with a $2000 bill for an MRI). I was panicking about the cost a little but my insurance did eventually cover it. If I hadn't had insurance then they would still have taken me and I would have been stuck with the bill. Some religiously run hospitals have charitable donations that cover the costs for those who can't pay. Most hospitals do not.
Related: My son was ill with a stomach bug, at a different time, and needed an anti-emetic. Even with insurance the charge for the meds would have been $165. At the time that was a lot so I took the option to just get a half bottle for just over half the price - I could buy another bottle later if needed. Fortunately, he didn't even need the whole of the one we did get. That $90 was with insurance. We could pay it but anyone who couldn't would be out of luck. That's for a sick kid.
I have a medication that, without insurance, costs $1,500 a month. My insurance and my employer cover that. I wouldn't be able to pay it. There are cheaper, much less effective, alternatives. If I didn't have the insurance then I would have to go with one of those with increased risks to my well-being.
So yes, people are left to die for being short of cash but there are some safeguards.
Medicare is federal healthcare for people over 65, some disabled people under 65 and people with end stage renal failure (I don't know why that one condition specifically). Medicaid is for low income people in certain categories such as childen or pregant women. Someone is considered low income if they earn less than about $1,500 a month. A healthy, non-pregnant adult would not qualify, even if they earned less than the low-income level. They are the ones who have to choose whether to call an ambulance or not and who will be hit with massive bills.
BTW: my problem turned out to be a detached retina. All fixed now. I hope your Mom continues to be well.