People in the north can keep driving in the snow because they’re prepared for it - the roads get regularly de-iced and plowed. In the south, it’s just more treacherous... Also, snow is more likely to turn into ice when the temperatures are closer to 32 degrees than when they are 10 degrees. In any place that isn’t prepared for snowfall, a little bit can cause a HUGE problem.
You’re right about the snow being more treacherous in the south. I think it is because the ground may be warmer and when the air is cold the snow flakes freeze into a black ice.
I never used to believe that there was a difference but I do now. A few years ago I was driving up from Charleston in the freezing rain, pooh-poohing the southerners who had warned me not to drive. All of a sudden I saw that all of the big tractor trailors were pulling off the road. Every one of them pulled off. Truckers know.