The brainwashing of Americans is a predictable outcome of polarizing media and echo chambering.
When the news outlets are consistently biased, overtly, to the right and to the left, then people without much critical thinking skills are eventually saturated by a constant diet of NYTimes, Fox News, PBS & NPR, the Washington Post, and the rest.  All of them are nakedly propagandists.
My brother was here two weeks ago working with me.  I was dumbfounded when he rather plaintively protested that he didn't know who to believe.  It was in response to some comment I made about Trump and the coming election.  He lives in a bubble in Arkansas, surrounded by uneducated people, no one around him even having a college degree.  He served briefly in the Army and before that in the Navy, but has always worked blue collar jobs and gone to Fundamentalist churches. 
And he's a fan of Christian radio, and it's been a shill for the GOP now for decades, so he can't tell the difference.  
Sadly, like most politics, the people at the bottom believe propaganda while cynical people at the top, on both sides of the aisle, know better.