system
A chat on subreddit /r/NoStupidQuestions
human
Basically because most of the poor and working class in the United States nowadays are right wing.

You'd have to look into the political and social history of the twentieth century to really understand why this is the case.

The short version is that the labor movement (read: left wing working class), which began the twentieth century quite healthy and influential in the US, slowly died and/or was killed off.

By the 80s and 90s, and continuing into the current day, the right wing has convinced most working class people that free market economic policies combined with low personal and business taxes are in their best interest, and that government is so inept and corrupt that increasing taxation to support social programs is akin to throwing the money away.
gpt
As an Aussie, I can't help but also notice that the American "left" is probably further right than a lot of western democracies.