Will Smith....jeez. The same guy that when Spike Lee called him and tried to be hired as the director of ALI, Smith didn't want Lee to make his "type of film" and instead wanted a movie that would have "broader appeal"...of course ALI tanked in theaters anyway, even with a personal favorite filmmaker of mine, Michael Mann.
But yes, Spike Lee was a student under Scorsese when "Marty" was a film professor at NYU. Ironically, Oliver Stone was also a student.
Another example of a filmmaker that does what he knows is Quentin Tarantino. I mean most of his movies set, or partially set, in Los Angeles where he was raised and lived for most of his life.
But yes Turnbull, you are absolutely correct, and most Hollywood movies have these cliches either because they were too lazy(director/screenwriters/producers that is) to do proper research or actually know these people, or they are really not cultured enough to know any better.
Some filmmakers that at least attempted to go for a difference was George Romero, who had the black lead in his horror classics NIGHT OF THE LIVING DEAD and DAWN OF THE DEAD(Ken Foree For President!!!), and John Carpenter with Austin Stoker in ASSAULT ON PRECEINT 13.
Of course Tarantino is another man who tries, like look at his female black lead with Pam Grier in JACKIE BROWN, and of course letting Sam Jackson do his thing.
But again, the racial stereotypes...thats why many African-Americans were taken for the "blaxploitation" films of the 1970's, for they for once were the heroes and not the sidekick thats says "Damn!" all the time(like we see the norm in Hollywood movies now) nor were they the token characters. I mean Larry Cohen's BLACK CAESAR is basically the same story of SCARFACE but instead a black hood, with guts and intelligence and street smarts, takes command as a major mob boss over an Italian syndicate. Besides, look at the "Bad-Ass" heroes in movies like SHAFT, SUPERFLY, TRUCK TURNER, and so on.