@Curvin
First off:
She is literally a mystery meat in the show too, so WOW... You have no idea how perfect of a description that is.
Second: Because they are racistsm who ignore all non-humans in the galaxy.
@Curvin
BTW, I remember quite clearly when I was a kid, that even though, I clearly knew what a race is, I remember not seeing Mace Windu as a black person. The concept literally didn't connect, until I heard somewhere, that he was played by Samuel L Jackson.
Because, that is the power of fictional story telling. It can envelop you in a world, where these concepts do not matter.