[Steve_Seattle]

"Another comment: on television, you will quickly notice that there must be a black person in every single commercial."

It's not just black people, many commercials try to include all major racial groups and both sexes by splitting up their messages into small fragments, each of which is spoke by a different person, e.g.,

We at IBM (white female)
are committed (Asian male)
to a future (black female)
in which new ideas (white male)
are welcomed (Hispanic female)
like the rising sun. (Asian female)
We are IBMers. (group shot)

[SkyPilot]

We at IBM (white female) are committed (Asian male) to a future (black female) in which new ideas (white male) are welcomed (Hispanic female) like the rising sun. (Asian female) We are IBMers. (group shot)

True.

And every white make is depicted as a stupid bumbler.

They even have a name for them. "Stupid Man Commercials."