That is altogether false. It doesn't agree with the lived experience of millions. Just wait until it happens to you, and it will.
I do agree that a lot of people seem to believe that’s how it works. There’s some objectively correct treatment, the doctors uncover what it is, and I have an unconditional right to get that treatment no matter what it costs. But no healthcare system does or could work that way. You have to consider tradeoffs and control costs somewhere.
You can build a system that makes it seem that way to the patients; that’s why I like Kaiser. In my opinion it’s more user friendly that way. But the tradeoff is that cost controls are imposed directly on what doctors are willing to prescribe. There’s many stories of Kaiser doctors refusing to prescribe expensive treatments that other doctors would, because as a matter of policy they believe some lesser treatment would be sufficient.
To be clear, a lot of people have very valid complaints about the US healthcare system. I'm not saying everything's perfect or even that every improvement would involve a tradeoff. But every medical system on the planet, including whichever ones you have in mind as better than the US, has controls on how expensive drugs can be used when cheaper ones might work.
For non emergencies, I would much prefer we go back to patients paying cash, and getting medical loans when they need. For emergencies I would prefer the government cover them directly without any intermediary. Because of the insurance system, things cost 10x more than they should, which makes it an actively harmful system. If it were to go away, competition and efficiencies would drive down prices 10x.