I’ve yet to travel to a country of 330 million people or more with flawless public healthcare. Perhaps you could point me to one?

Well there's only two other countries with more than 330 million people so that's a bit of a poor argument to make, and it assumes that the well-functioning systems in (most, if not all) other western countries won't scale - I'm not entirely sure where such an assumption comes from.

Probably a refusal to imagine it as a possibility in the first place, I suppose.

National level public healthcare would be difficult to implement in the US for the same reason a pan European standard would be hard to implement.

That said, if you do it on a state by state basis then qualify will vary just like it does between the different European countries.

But as the US is a single nation, the mere existence of variation will mean some people say the system is a failure.

Because it working in smaller countries means it could never work in a large one?

But, why not? How is population size relevant?

Well "flawless" is obviously a disingenuous expectation on your part.

I would direct you to the United States which has a pretty amazing public healthcare system called Medicare that has an 80+% approval rating among those lucky enough to be on it.

Did you miss the sarcasm?