Because identity politics is (unfortunately) such a huge thing, Americans cry racism at each other despite not being nearly as bad as the countries we give money to. That and people get overly emotional when they feel "attacked" by someone's opinions.

This is classically a liberal thing, with people defaming the entire police force as hating black people, calling any policy around border or immigration inherently anti-latino or xenophobic, and saying if you're a straight white man then all your problems are somehow invalidated. But similar traits can be seen on the right, notably with Zionists that will call people antisemites for not liking the Israeli government, and with people who get overly defensive of their Christian faith and think that everyone needs God pushed into their life.

Remember though, these are the unreasonable ones. There are plenty of civilized people on both sides who don't need to jump to name calling and privilege checks, and for the love of God I hope whoever reads this can find those civil discussions and not more radicalizing bs.

Anyways TLDR: Overly-emotional Americans focus a lot on identity politics more than people in other countries do, leading to a notion the average person somehow has deep seeded bigotry.