But what’s even harder for me to understand is why so many Americans seem to exclude and racially stereotype other Americans solely based on their appearance that has nothing to do with their personality.
You likely know the USA's checkered past with human slavery of Africans, so I won't go into that, but thats great example of what I'll cover.
Besides the tribes of Native Americans that have been here for millennia, all of us are immigrants or the product of immigrants past. Each subsequent wave of migration has had a semi-dominant culture that then worked to "fuck you, I got mine" to immigrants from later arriving groups. Historically while we absolutely discriminated against people of color, its not just skin color that we did this too. We did this to the Irish. You can see here that by this time German immigrants were acceptable and even preferred at the same time Irish were discriminated against:
source NYT 1854
Then 50 or so years later we did this to Italians, and some of that discrimination came from Irish were faced much of the same hate years earlier.
1903
...and on and on.
Its not just race though. Even in USA women didn't have the right to vote until 1920 with the passage of the 19th amendment. Homosexuals couldn't even marry until 2015.
In short, most of us are dragging the least of us to a position of understanding of equality and equal treatment to all Americans evenly. While I'm very happy about the key pieces of progress we've made (Civil Rights act of 1964 being one), We have a long way to go yet. Discrimination in the USA is still a huge problem we need to fix.
Other nations may not discriminant based on race, but on other things.
- UK has a history of discrimination based on societal class
- Canada has a history of discrimination based on preferred language
- India has a history of a caste system
Other countries yet discriminate on religion. Humans have a habit of choosing in-groups and out-groups, and then centralizing power to the in-groups to the detriment of the out-groups.