This answer may be hard for some Americans to swallow, but the current health care system in the USA is a legacy of slavery.
Think about it from an outsider’s perspective, the rest of the developed world has legislated towards universal health care, but the USA is the only outlier. Moreover, the USA was the only developed country with such a large slave population per capita. They didn’t want freed slaves to vote, nor go to the same schools or live in the same neighbourhoods, and Jim Crow laws persisted into the 60’s.
Considering all this and many more mechanisms of oppression not mentioned, do you think the bourgeoisie and those in power have any interest contributing for equitable health care for this segment of the population? Of course lobbyists and not wanting to “take a pay cut”, as others have answered, are a huge factor preventing change at the moment. But this is one of the many legacies of slavery in the USA.
Other anomalies like guns laws and tipping for service in the USA can be explained the same way. Many cultures can claim the need for guns because of hunting culture, but the USA has such a large underclass it was threatened by, and the culture of guns persisted, just as it does in many developing nations with a large underclass.
Regarding tipping, freed slaves were not allowed to earn a wage as porters initially, and as a result could only earn tips. Now the practice of tipping persists today in the USA hospitality and service sector and new comers must navigate a complicated tipping system across society as opposed to just having businesses pay a livable wage.
The legacy of slavery can also be used to explain the poor welfare state, the high prison population and many other anomalies in the USA, when compared to other OECD/developed nations.
Edit: forgot mention the electoral college as well