Since the 1960s, due to the combined effects of television entering our homes and the bitter struggle for minority rights that challenged the power structure between American citizens, politics has devolved into a spectacle modeled after team sports, with strong brand-identities devoid of nuance and contemptuous of cooperation between sides.
While there has always been income inequality in America, there was an ethos of "we're all in this together" through to the civil rights legislation of the 1960s. In the 70's the mistrust of government was canonized by the Vietnam War, Richard Nixon and the Southern Strategy of the Republican Party, which used racism to siphon off white voters.
The programs of the New Deal in the 1940s were perceived as helping every-day Americans and were therefore supported by all but the most craven oligarchs. But in the 1980's Reagan shifted the identity of the recipients of entitlements to "welfare queens" which was a DOG WHISTLE implicating black inner-city women who collected government checks. The advances of the Civil Rights movement ushered in resentments that the GOP has nurtured to this day.
The GOP of the 80s not only railed against entitlement programs but union workers and middle-class workers as well, and eventually set its sights on the Government itself. The GOP envisioned a world of privatized institutions, with charitable work handled by churches. Ronald Reagan declared that Government was the problem and not the solution. This lead his successor, Bill Clinton to swing the democratic party to the right with policies dismantling the New Deal while maintaining a left bent with identity politics. This has further divided the two political parties. Abortion was also used in the 1970s to divide the nation. The Republican Party and the Tea Party and the Freedom Caucus have since become shills for privatization and corporatism, the perfect result of a century of Commercialism.
With the advent of Cable news in the 1990's, the common American narrative was divided into left and right, with the GOP establishing a populist narrative at odds with its policies which in fact demean workers, the environment and civic life in favor of a corporatist agenda wrapped in a flag of freedom. Identity Politics on the left are so aggressive that they reinforce the cultural divide.
Reinforced by a ubiquitous Media environment that fans the flames of division to increase viewership, the increasingly rigid agendas on both sides of the political spectrum reduce politics to a contest in which winning is the end-in-itself. This trend has decreased any hope for bipartisan cooperation and imperiled the lives of our nation's citizens.
Why the Right Went Wrong: Conservatism--From Goldwater to Trump and Beyond by E. J. Dionne J.R.
What's The Matter With Kansas by Thomas Frank
Hillbilly Elegy: A Memoir of a Family and Culture in Crisis J.D. Vance