Re: And that's probably why...
There might also be some cultural sensitivity in Hollywood around using actors whose ancestors were enslaved to portray robots. The meaning of the word 'robot', coined in a play by Karel Capek, is derived from a Czech word meaning 'forced labour'. For analogous reasons Louis Prima was chosen by Disney to voice King Louis in the Jungle Book instead of Louis Armstrong.
In Anime, black androids are rare probably because Japan has an ethnically homogeneous population.
Capek's robots were actually androids, akin to those in Nolan's Westworld or Blade Runner (organic and squishy, but assembled not grown). Conversely, Google's Android logo is actually a robot. And annoyingly, Google's GBoard doesn't present a 'C with upside down hat' ( unicode U+010C ) for Capek's name.