Edit: Comments so far have focused on the speech of politicians. While this discussion is interesting, and desired when relevant, I am more concerned with use in activist communities. I believe the connotation is different: unlike politicians, these people are not trying to sound more 'folksy' or 'of the people'.
I often hear folk used in leftist and activist communities. The word choice seems ideologically motivated, a more politically correct synonym for people — just as one would say 'differently-abled' instead of 'disabled' or 'latina' instead of 'hispanic' — but I can't determine any need for the substitution. Is people offensive? The most common use is in 'black folk', but also 'white folk', 'brown folk', 'queer folk', etc.
My fundamental question is this: Why is folk used more often in activist communities?
I recognize that I don't have hard evidence to demonstrate the truth of the phenomenon. I'm not sure what evidence I could provide. So let's all play together and assume it is true?
I can imagine two answers to this question.
- Folk is a politically correct substitute for people. Why, then, is people offensive, and folk not?
- The word choice is not ideologically but historically motivated. Folk is historically common in the black community. As non-black people interact with black vocabulary, they assimilate (either naturally, or because of a false believe in #1). As listening-oriented black/non-black interaction is more common in activist spaces, the use of folk has spread quickest in activist communities.
These are, however, simply unfounded hypotheses.