I'm on mobile so I didn't read the pdf.

But I'd say related to the itle is overly PC people highly vocal aka SJW as people say. It's the left equivalent of far right.

The other thing I think is US style politics as a Canadian it amazes me that is is so absolute you're Democrat or Republican. Most western countries have multiple political parties covering many shades politics.

People in the USA from my viewpoint seem to have become convinced they can only be one or the other. And it seems there is a huge gap between the two parties more than I can recall seeing.

The other thing is the US president is treated like a king he's just a politician. In western countries with prime ministers he can be thrown out easily and most people don't care who the person is.

Age also seems to be a big part maybe it's a Millenia/Boomer thing big groups with opposing views.

And of course there seems to be a huge lack of trust about what to believe. The tackiness most paranoid websites which years ago were called trashy tabloids are now seen as actual journalism. A person claiming to be a conspiracy theorist acts as if it is a badge of pride.

Overall I don't know lack of education, no mentors, lack of direction, lack of a moral guide.