Nothing new, the Seattle area has had crappy drivers forever. I noticed it when I first moved to WA in the 1980's, the drivers here certainly haven't improved with time. According to Allstate statistics Seattle has some of the worst drivers in the country.
http://komonews.com/news/local/report-seattle-drivers-among-the-very-worst-in-the-nation
It's obvious every time I drive out of state and (unfortunately) have to come back. As soon as you cross the state line into WA and start seeing more WA plates the drivers get worse and the closer you get to Seattle the worse they get.
About a mile from my house is one of the big school bus stops, it's on large, open visibility, hairpin corner. Literally half the people going around that corner can't do it and stay in their own lane, going right or going left doesn't matter. It's no wonder there are so many accidents when half the people can't handle something as basic and following a curve and staying in their own lane.