In Houston, Tx, snow is rare, but it does sometimes happen.
All it takes is 0.001mm of sno, and the city is grid-locked.
The local TV stations have helichoppers showing stationary traffic on 5 lanes each way on the 610 loop.
Thing is, they don't adjust their driving style to suit the conditions.
They just continue to drive at 60, bumper-to-bumper, and then 'Woah! What happened there!" when they hit ice on the over-bridges.
Go to Colorado, and they know how to deal with, and drive in, snow.