The real arguments only rarely get stated by politicians, and it's the reason we don't get other universal services, either. It's ideological. The economic efficiency, competency, or access arguments (government can't do anything right, it's wasteful, etc.) while they do get used (and are certainly believed to various degrees) aren't the core (cultural) reasons. They are a belief that:
- society should be dog eat dog, red and tooth and claw, and that the weak and sick should merely die. Not only is that not bad, it's desirable, as the weak and sick bring down the rest and having them disappear strengthens the society / species
- the world should be every-man-for-himself, that you should be on your own, and never expect anyone to help you outside of blood relatives, or if you're lucky, charity.
- that everything must be "earned," discounting the ideas that it's society itself and all of its trappings (trade rules, police, roads, availability of skilled workers trained with public money, etc.) that's allow said money to be earned in the first place. If you don't earn it you don't deserve it, regardless of what that means for you.
- that government should simply not be in the business of providing services, period. It should exist only as a nightwatchman state that protects from "force and fraud" when it applies to domestic policies (empire building and maintenance + policies to further theocracy and political chauvinism are a big divide over spending on the right)
- taxation is theft. If one "earns" money, one should be able to keep basically all of it (minus force+fraud taxes, though ancaps don't even want that one.)
Now, mind you, this doesn't actually reflect the will of people in the US (recent poll links: https://twitter.com/GunnelsWarren/status/1078510910317174785), but large parts of the right-wing establishment (many of which inhabit the Democratic party, not just the Republican one.) This includes large donors, corporations, and powerful think tanks.
One thing that has to be understood about the US, is that since its very founding, it has largely opposed redistribution (the General Welfare clause notwithstanding.) People should remember Madison:
"Landholders ought to have a share in the government, to support these invaluable interests, and to balance and check the other. They ought to be so constituted as to protect the minority of the opulent against the majority."