Uhm, the show is set in an alternate universe Harlem of roughly late 60’s/early 70’s vintage. Which was pretty much an all-black place. Luke Cage would have had to be set somewhere else to have many white people in it, and, well, then it wouldn’t be Luke Cage, since the whole point was that he’s, well, a black superhero from Harlem.
Funny how these very same white people had no such complaints about a lack of diversity in Seinfeld, eh? How… white… of them.
– Badtux the “They need to take off their bedsheets” Penguin