Racism and TV are as old as TV. Racism alone, of course, was invented with radio. But there was a good deal of time during which you'd never see anything even remotely multicultural on TV the vast majority of the time, and people thought they were being pretty progressive by watching Benson. And then they'd watch All in the Family, and that was OK because Archie Bunker, though racist, was also a twat, so when he met Sammy Davis Jr., you always knew Mr. Davis Jr. would come out of it OK. Time passed, sitcom producers started realizing you could feature characters who weren't whiter than bleached Wonder Bread and the world was a fine place.
And yet, even today, in 2012, you can find shows creeping around that seem to not just exist in a vacuum, but revel in just how intolerant or ignorant of race they are.