I just wanted to share a quick anecdote. I'm trying to arrange a carpool up to a union meeting in Berkeley this weekend, and one of our organizers mentioned that only one other person would be making the drive, and his wife would be in San Diego with his car. Therefore, I'd "have to be okay with taking [my] car."
This is from a person who always sees me on my bicycle on campus, and who, to my knowledge, has never seen me behind a steering wheel of any sort. It is simply assumed that, being a productive member of society who makes a decent living, I own a car.
I had a similar experience at Altura credit union not too long ago. The woman who helped me open an account told me that her credit card printing machine was down, but that the branch on Central would be happy to help me. When I asked how to get to that branch, she said "Oh, you just get on the 91 and..." This is after we'd had a conversation about the fact that I am car-free, and had arrived on my bicycle. She also seemed rather skeptical of the fact that I could ride a bicycle all the way to the Riverside Plaza.
The point here is that automobiles have woven their way into our psychology. We simply assume that everyone who can afford one has access to one, and will naturally use it during the course of their daily lives. This is an assumption that we need to correct.