Most dogs are racist in that they don’t like people that are different from what they are used to.
Living in Thailand, the only time I ever got bitten by a dog that was not my own (breaking up fights or whatever) was clearly because I was not Thai - attacked me from the back and bit me on the ass.
Many dogs don’t like people in uniforms or disabled folks. I’ve raised dogs that dislike or get aggressive with men with beards or people wearing hats. Of course many don’t like kids, and many show a preference for either men or women.
It’s all a pack thing isn’t it? Dogs don’t see race, heck they don’t even make distinctions about species. It’s ‘my pack’ or ‘not my pack.’
My dog is not racist. She barks at everything and everyone who walks in the door. Even me.