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).