>It’s unclear to me why the American government doesn’t change the laws and create a new system more like a European one

Because the regime decisions in the US. are much defined by the corporatocracy and lobbyists interests rather than the people's. Some further readings/videos on that:

[0]: https://harpers.org/archive/1960/10/the-politics-of-medicine... (The Politics of Medicine)

[1]: https://www.youtube.com/watch?v=RoHq6dBpxYU (The Lobby)

[2]: https://chomsky.info/20100124/ (The Corporate Takeover of U.S. Democracy)

[3]: https://chomsky.info/20110407-2/ (The State-Corporate Complex)