This question was posed to me, and the answer is pretty simple: People in California very often do use their turn signals.
In California, though, the turn signal is a challenge. It has nothing to do with being inconsiderate or laziness. It’s a peacock showing colors, or a baboon showing it’s big colorful butt. It’s an aggressive challenge to the person in the next lane: “go ahead, try to stop me.” The driver in the next lane can either submit to the dominance displayed by the signaling driver, or issue a formal challenge in the form of acceleration.
Real estate on California’s freeways is at a premium, and allowing a vehicle to occupy the space in front of you that rightfully belongs to you is testament that you have no testosterone, and your lineage will die out. This is especially true if you acquiesce the turn signal challenge from a Toyota Prius, which will – after moving into your lane – proceed to demonstrate it’s dominance over you by driving 15 to 20 miles slower than traffic around it.
This is why I drive a Jeep with an big-ass aftermarket steel front bumper marked with the lost paint from the side panels of countless Prius challengers who learned the error of their ways…
Be safe out there. See you on the trails!