The choice in CA is lane-split or sit in traffic hours a day with the cars. Once you get the 'nads to do it (and it takes a little while), you find out it is infinitely safer than waiting for a car to climb over you. There are just too many people driving cars here.
Wrecks sprinkle the highways and are a cause of much of the traffic congestion on the expressways (esp. at interstate crossings.) Even expressway exit signs, you are often given one mile time to react ONLY: not multiple exits notice. So if trucks are lined in front of your ONE sign's notice, you are screwed. ALL expressway exits everywhere are ONE sign's notice, and people freak out when they start to pass their exit swerving wildly so they do not take an hour in traffic (at best) to get back on course.
Everyone knows everywhere that wrecks happen in multiple occurrences because people get complacent and anxious at the same time. it's like blue-hairs (old people) and teenagers on spring-break in FL driving together: not good.
It would be almost impossible to live in CA without riding motorcycles if you commute daily, imo.