Those places don't have a hellish Frankenstein's monster combination of public and private and a load of regulations at the federal and state levels all adding up to high costs that have to be passed on to the consumer, but also weird niches of market inefficiencies that can be exploited by anyone who's managed to luck or judge their way into an advantageous position.
They also don't fund most of the world's healthcare advancements, which the US does.
They also cut off care at a certain point, whereas in the US you not only have access to most of the cutting edge treatments in the world that just aren't available on single payer systems, as they don't provide enough value, you also can find someone to pay to do it. You can bankrupt yourself on cutting edge treatments if you like.
I don't know what the answer is, other than "try again" and have a nice multi-insurer model, which I think one of the Scandies has, that just competes on efficiency and has its payouts and insurables defined by government, or maybe a single payer model. Or make healthcare a state-level problem and have each state solve it differently without federal overhead.
Healthcare is an inelastic service: people will pay everything to get it. So private hospitals in a free market are pushed to bill their services as higher as possible. Actually, their prices would go to infinity, if not limited by people total savings and earnings.
So, here the insurance companies make the problem worse: they give people access to "infinite" credit. So you can pay for those exorbitant prices. But with insurance you just increased the pool of money people can use for health, so private hospitals can and will increase their pricing. Add more free market competition and you get the disaster of the USA healthcare system.
Because of that reason, basic economics, is that for profit Healthcare cannot work long term. The only way to make it work is making it a public service. But in USA politicians will cry that is comunism, so they won't do it.
And the USA Healthcare problem doesn't limit itself to USA. As americans are unable to pay for healthcare there, they started doing medical tourism, which is making health prices in other countries more expensive too.