As someone that grew up in Pittsburgh and lived in the Seattle area for 5 years, Seattle's topography isn't that extreme, the drivers are just awful. My favorite example is this interstate exit: https://www.youtube.com/watch?v=Tij3SRs_5wg&list=PL_ZOHdoqrC...
Tires are the big thing. The vast, vast majority of Seattlites aren't swapping out for a winter tires set in winter, and they aren't running a 3PMSF-rated all-season / four-season / all-weather tire, either.