I don't know why anyone would think it can't happen here, it already did. It was called the Jim Crow South.
Black people were persecuted and if they got out of line they were killed, often very publicly.
"People are people, so why should it be?
You and I should get along so awfully
People are people, so why should it be?
You and I should get along so awfully
So, we're different colors and we're different creeds
And different people have different needs
It's obvious you hate me, though, I've done nothing wrong
I've never even met you, so, what could I have done?"
The idea that people are inherently good is in conflict with a lot of religious dogma to the contraary.
Original Sin, we are all born with a black mark on our ledger.
People are better or worse because of both Nature and Nurture. Nobody is born a Saint, to be a good person is hard.
TEK