There are two simple reasons for this that make all the sense in the world:
1. Television is generally aimed at a market of minority viewers with lower-than-average intelligence.
2. You'd be hard pressed to find a racial/demographic group that is LESS likely to be swayed by a TV ad than white males.
Perfect case in point for #2 ...
I think the Chevy truck ads built around Bob Seger's classic "Like A Rock" collectively are the best ad campaign in the history of television. And yet I've never even considered buying a Chevy/GMC truck.
The effect can be indirect — if you speak well of such trucks that’s advertising for them too.