Trucks, cars, motorcycles...there are plenty of crappy drivers in all three catagories. I will never understand though why in God's name someone will be driving along in the passing lane and slow down, matching speeds with the car or truck they're passing, traveling along beside it. What the H*!! is that all about?
One thing I will say about SoCal drivers though is that they understand how traffic works and, for the most part, seem to do whatever makes it flow the best. Example, alternate merging when a road narrows to one less lane. Here in Oregon people will move into a single file 2 miles before it's necessary and do everything in their power to prevent anyone from merging or using the clear lane...including moving over into it and blocking it. Self appointed merge monitors I guess.
Sorry...I'm ranting. We have construction nearby both N and S bound on our only freeway (I-5) and it's driving me nuts!!!