Most Helpful Girl
Good question. There have been 19 seasons of The Bachelor and 11 seasons of The Bachelorette, and not one of the bachelors or bachelorettes have been black.
I can't speak for the past, but recently, "fan favorites" are picked to be the next bachelor or bachelorette. Since there aren't many black contestants (only like two per season), black people don't have much of a chance at being a favorite. And to be honest, I'm pretty sure most of the bachelors/bachelorettes are more interested in marrying within their own race, leaving a cycle of white people running the show.
Personally, I think it'd be awesome for the show to have some more diversity. I also liked back when the bachelors were picked more at random (like from videos/interviews) and not from just being fan favorites.
Most Helpful Guy
This is one of the most astute and interesting questions I've seen on GAG.
America would be a very different place if we were actually capable of having a black Bachelor with white contestants (or a strongly diverse group of women, including several whites). That this is still borderline inconceivable shows (among many other things) how far we have to go as a nation.
As a white American boy whose godmother is black, all manifestations of racism and prejudice affect me deeply, but the asker is pointing out a facet of American life which is way more important than an odious reality show on TV.
Anyway, as @Luv2BRealExotic13 said, the answer is quite simply, "We couldn't handle it." That's what it all boils down to.