i'd say it's christianity or the concept of natural law that's historically been pushed by christianity.

it roughly says that there are natural laws that are derived from god (i.e. unchangeable circumstances) and are therefore unchangeable themselves. they typically revolve around (political/military) power being the center and origin of all law; it roughly corresponds to the nazi principle "might makes right" which says that if you're too weak, you have to adhere to stronger people's rules.

that historically influenced US politics a lot. that's why you have the modern concept of "when people are 60 years old and they get sick from cancer, well that's natural and therefore good and therefore we shouldn't do anything about it." i think that's the major influence, not so much about shareholder value.

in fact medical companies would make a shitton of money if they treated every disease. it's actually hurting the economy that the US does not spend more money on social healthcare. but ideology seems to be more important to the US government in this case.

edit: eh after reading the above wikipedia article it speaks mostly about the medieval concept of natural law but that's not how the term is used these days. these days the term natural law mostly refers to things such as anarchy (as it's used by the media) and doing away with a (human-made-rules)-based world order. in other words "eat shit, be free" but for politicians.

it's used like this: "i am a politician. i want to suppress other people. because i have this natural urge, surely it must be a natural thing to do. that's why i do it". while things that would limit this behavior such as democratically elected laws and human-made laws such as the legal system are ignored because they are "not natural and therefore not to be taken too seriously". trump is the best example of this.