To get away from ghetto hood types. In some small cities there are no really decent apartments (those which are not infested with fire ants/roaches). Cheap places are extremely rough on the east coast. At least if you get a trailer, maybe on your own lot away from the community, you can live a somewhat civilized existance w/o being murdered or living in complete filth of your neighbors. It is also nice to be able to walk outside on your remote lot and not have to look at these people either. Nor their trashy kids, cars, friends lol
Better than apartments in some circumstances....until tornado comes 
Most "trailer people" like in
trailer parks, though, not on their own lots. As far as I know, those places are just as bad as the apartments you describe, for many of the same reasons.
