Whelp, we started watching last night. At least some of the cultural aspects in terms of how low income rural people live and think can be found right across the country, and even in parts of Canada, so not exclusive to the southern US (full disclosure: I grew up in Arkansas). We've even got cats tear-assing around the roads in jacked-up pickup trucks festooned with confederate flags here, and for that matter plenty o' gun nuts shooting up traffic signs on lonely country roads (though gun ownership isn't nearly so prevalent), and baptist right-to-life bible-punchers galore. The music is quite an interesting aspect, I'd never heard, or heard of these particular acts. Not sure if it reflects the living culture any more except in a nostalgic, hipster-hillbilly kind of way. Anyway I enjoyed it thus far and looking forward to watching the rest.
It got considerably more intense after the 40-minute mark (which is about where we had left off) with the jesus nuttery completely out of its cage. Yeah, this may be unique to the south but I dunno, never witnessed it first hand there or elsewhere, definitely a subculture. Maybe has an an analogue in places like Iraq and Afghanistan... Well made film, fantastic cinematography, didn't really connect the dots, for me at least.
Another thing: everyone in the film is white. So there's that.