I grew up in Maine, but lived in Florida for 3 years. While in FL I found that temperatures of even 50F would make me shiver, while in Maine thats shorts and t-shirts weather. Humidity works both ways, it makes your hots hotter and your colds colder.
As for the snow; places that regularly experience snow and ice are ready for it. The states, cities and towns all have fleets of trucks ready to plow, salt, and sand the roads. The salt doesnt always just wash away, it dissolves with the water, and some of the water absorbs into the road itself.
The roads themselves are also different. there is a point when heading south that you might notice the road has changed from the tar/asphalt that they use up north, to concrete, or something similar. That is because the tar will melt in the high heat of the south. So why dont they use concrete everywhere? becuase the concrete absorbs more water than the tar, so when it gets cold there, it freezes over faster, creating more ice on the roads. Have you ever noticed signs on a concrete bridge that say "Bridge freezes before road does"? This is why.
2 inches of snow may not be much for people who are ready for it, but for areas that are not, it is very dangerous.
TL;DR: The south have roads that freeze over faster because they are made of concrete, the cities dont have plow and sanding trucks, and the people dont know how to drive in snow.