Yeah, as the other said, just on the main roads. You have to remember, in the Northern US, they stock up on salt and sand in preparation for the winter. They also have fleets of plows, salt/sand trucks and the like. They get used, and used heavily from November - March.
In the South, those trucks would be just sitting idle for all but 2-3 days a year so the state and local governments can't afford to have a huge number of trucks. It just doesn't make economic sense and thus, when the snow/ice hits, they can only handle a portion of the roads. On top of that, most cars aren't equipped with the best tires to handle the weather.
