BMWs are the most prevalent in the San Francisco Bay Area and Los Angeles/Orange County where there's heavy commute traffic that's often bumper to bumper so an automatic is preferred by most even those who would rather have a manual.
In LA there are no expressways - just freeways and boulevards with lots of stop lights so you often need to drive cross town in heavy traffic with lots of stop lights.
I live in the Bay Area and traffic is now somewhat lighter because of the "recession" and it's now summer with school out and folks on vacation.