Who do smilin' man and cameraman work for in "Blues Ain't No Mockin Bird"?

The two white filmmakers claim to have been sent by the county to make a film about food stamps. They appear to be operating on the racist assumption that the Cain family, being African-American, is on welfare, and is therefore the ideal subject for their film. Grandma Cain takes exception to the filmmakers' presence, seeing them as nothing but a nuisance as they trample all over her flower beds. They make patronizing observations about Granny's vegetable patch, blithely unaware that this is proof that the Cains are hard-working, self-reliant folk who have no need to be on welfare.
Granddaddy Cain is not much happier than his wife at the filmmakers' intrusion. These men are trespassing on private property, and he wants them to leave at once; It makes no difference whether they're working for the county or not. In any case, Grandaddy Cain doesn't take kindly to the government infringing on his rights as a citizen. In asserting his rights as an American, he is challenging the stereotyped view of African-Americans that the filmmakers and their employers clearly hold. Far from being reliant on the state, he wishes to assert his independence from it.