As a citizen of a country with a universal, publicly-funded, health care system, I can tell you that it isn't a panacea. It doesn't resolve all health care problems. Although health care costs are drastically lower in Canada, there are trade-offs. This Wikipedia entry provides a pretty good comparison between the two systems:
https://en.wikipedia.org/wiki/Comparison_of_the_healthcare_systems_in_Canada_and_the_United_States
I don't know if this is much of an issue in the US, but it certainly is in Canada - wait times. One way of controlling costs is to ration care. For example, a few years ago, my wife needed an MRI on her jaw. Since it wasn't considered an emergency, she would have to wait about a
year to get it. So, she went to a private clinic to get it done, at a cost of about C$1000. Since this is a service (nominally) provided by the public system, our private insurance is not permitted to cover this cost, so it came out of our pocket.
But, make no mistake, if you require urgent serious treatment, i.e. cancer, emergency surgery, life-threatening infection, etc, you WILL get it and right away. And, that care will be the same top-notch quality no matter your economic status. My family has private coverage from two insurance providers - one, as a result of being a retired military member and the other through my current employer. This coverage is for items not covered by the public system - prescription drugs, vision, dental, etc. The premiums and deductibles are quite low, because family doctor and hospital care a paid for by the public system.
I broke my arm at the wrist a couple of weeks ago, due to a slip and fall. I went to a comprehensive health clinic near home, where they set my arm in a cast. Because it isn't an all-encompassing hospital, they had to send the post-casting x-ray to the orthopedics dept at the hospital downtown for their blessing. Well, they didn't like the positioning of my wrist, so I had to go to the hospital to have it reset.
Because it would be rather painful to have the first cast removed and resetting my arm was - in his words - "going to be a bit more violent", the orthopedic resident said I would need to go under conscious sedation. When I came back to my senses, the first one was gone and a new rather club-like gargantuan thing had replaced it. The doc said it had to be that way to maintain the positioning of my wrist and he was still concerned it might require surgery. He said he would discuss it with the orthopedic surgeon the following day to get his opinion. in the end, I didn't require surgery. I saw the surgeon a week later and after an x-ray, he said he was happy with how it was progressing. I saw him again this past Tuesday and, after another x-ray, he said I could get a lighter cast put on. Being keen to get rid of my club, I said yes. However, this being done under the public system, the government only pays for a plaster cast. I had to pay the pharmacy imbedded in the hospital C$17 for the cost of the fibreglass, which I was happy to do.
Other than the cost of the fibreglass, there was no other bill to pay and no insurance forms to deal with. For all its faults, I'm glad we have publically funded universal health care. All developed nations should have this, by default. Nobody should be heading for the hospital wondering how much their care was going to cost them.
But, I think the Democrats' might be a bit too ambitious. If they want any chance of getting there, they might have to make the process more gradual and perhaps not as comprehensive.