I think the only reason NJ is on top of that list is because folks who live outside of NJ don't understand how to drive whist travelling in my glorious state.
Especially the folks from New York.
If you know what to expect in NJ, then you have a better chance of surviving the traffic here. Plain and simple.
I think it probably stems from the fact that New Jerseans simply hate tourists and out of staters, generally speaking, of course!
-Z-man.