Bill Cosby and his family were comfortably middle class in the TV show. I think he was a doctor. His wife was educated, the kids were thoroughly integrated, and they all wore expensive and elaborately-patterned sweaters.
This was a deliberate choice on Cosby's part, in order to model a middle-class lifestyloe for people who didn't have one.
The Jeffersons and Sanford and Son Both produced by Norman Lear as "All In The Family spinoffs, both were very sucessful.
But what are you doing, wanting TV to explore anything too close to real life, anyway? I don't think most of the TV-viewing audience can approach real life with any sort of comfort. They get to have that, right outside their door.
All of Norman Lear's shows dealt with real issues. The humor allowed us to look. Rosanne Barr did this as well to a certain extent-- MWC went for the cheap shot.