My understanding is that the poorest people are covered by medicare or get their fees waved (hospitals won't refuse to treat someone needing critical care). That is not "zero social net". Nobody is in fact jealous of the American healthcare system though. Meanwhile, in most countries in Europe, people live in fear of having to be put on wait lists that extend from months to years, or just plain being unable to access any care at all due to said systems being overloaded at times due to having much less overall slack (for example during covid).
Waitlists can be visibly bad in the UK but if you read German or French papers you’ll see complaints about “wait lists” that seem laughable by US standards.
I live in SV so can afford a level of health care well above the usual middle class. Yet I have a literal A/B test: my kid broke his arm in Germany and also in the US and the ordinary treatment he got In Germany was significantly superior to that at Stanford Hospital — ant at a fraction of the cost.