Clearly you have never been to the UCLA campus because, if you had, you would have known this isn't true in the least. You can walk all over that place.
The problem in LA is the culture. People believe they are to be seen in their automobiles and they buy or lease expensive cars and drive them ridiculously short distances for that sole reason (if there is another reason, please do share but nothing really makes sense).
I worked for a company based out of LA for 2.5 years and we were there often. One guy lived a 10 minute walk from the office but chose to drive each and every day. He didn't buy an M3 to have it sit in his garage, after all. Nope, it sat in the company's garage instead.