Mate, as I've said it's not one but TWO countries I lived in with Universal Healthcare, and you can't be a Nationalist (as you're trying to imply) for TWO countries.

If you're comparing like to like - i.e. the average poor disabled person in both a country with Universal Healthcare and the US - you're going to get some cases of those having insufficient treatment in countries with UHC (especially in those were neoliberal governments have been defunding their UHC systems to try and privatise Healthcare even against popular will, like the UK), whilst the vast majority of those people will be fucked in the US (unless they're Veterans).

I've lived in several countries and it's just an enormous peace of mind living in a country were you know that if you're involved in an accident and end up getting costly treatement in an emergency ward, you're not going to be ruined.

I think you're seeing the problems relative to a specific baseline and you think that there are massive problems there (which I'm sure there are) but the thing with the US system is that the baseline itself is way worse and all those problem you see would also be problems there but much worse (or maybe not, as those people would die a lot faster, at which point no problem would be visible) and on top of that in the US there are way more people with even worse problems when it comes to Healthcare than the "poor disabled person" in a country with UHC.