That and they absolutely cannot have people going out and interacting with such folks directly, that would break their entire narrative into pieces. Because once they see that those rural folks aren't mindlessly hateful, might even be "progressive" to some extent (lord did I know a few hardcore Dems down the Bayou) and are downright kind to their neighbors in a way cities don't have, they will be unable to keep up the charade of a boogeyman.

So you write movies that paint them as so insanely violent and territorial that people fear even driving through those places, and are on edge waiting for the shoe to drop talking to anyone around there.