I'm sure it isn't representative Stu. A documentary shows a limited, tiny vignette of a small area/section of the society of a country.
One might imagine that the UK was populated solely by drunks and football hooligans if one merely watched documentaries.

And this particular programme was principally concerned with investigating the KKK in some of the southern states. The gun angle was a side-issue in a way. America is absolutely enormous, and there must be a myriad of different people and environments there.
My husband is desperate to visit the States, so hopefully we may arrive there one day!