[krapp]

It's not really a commercial trope so much as a TV sitcom trope, going back at least as far as the Honeymooners.

It's also not as common as it used to be, as far as I can tell.

Edit: I've been thinking about it, and I don't think I can recall ever actually seeing "black male rescuing a white woman from a white male" being used in an advertisement, anywhere. Typically such a motif is used to present the black male as a threat, not as somehow heroically superior to his white counterpart.

Even then I can only recall its use in political advertisements (such as the infamous "Willie Horton" ad) and maybe very old movies.