I wasn't comparing the British and American attitudes. I was just commenting on the UK system. And that article suggests that I have exaggerated the British frustration with their health system. I don't follow it very closely and it's indeed possible I am conflating different things (e.g. frustration at striking nurses isn't quite the same as frustration with the system, although if the system makes it inevitable that the nurses will strike . . . ).
I think the larger point remains true, even if I chose a poor illustration: there are still policy questions to address within the category of "single payer health systems" and the way those policy questions are addressed have a big impact on the quality of the system and its citizens' perception of it.
I also suspect, though this is not terrible relevant, that Americans are just down about everything about America compared to other countries. Our president-elect rarely has anything good to say about the country, and shits on it with regularity. Trump shits on half of America with regularity; he tells invented stories of how bad it is; he calls America a Third World country or worse. So yeah, Americans are down on America. That's more or less unrelated to the point of your post.