The problem is that the US is not a true democracy. Because of lobbying (a form of legalized corruption) [1], big corporations are in control of the country. The laws are written by big corporations such as oil companies, big pharma, hospitals, gun manufacturers and so on. See revolving door [2].

[1] https://en.wikipedia.org/wiki/Lobbying

[2] https://en.wikipedia.org/wiki/Revolving_door_(politics)