If you look at places like San Francisco and the way wealth is pooling there, it's easy to understand why traffic congestion is growing faster than the economy.
If you put a bunch of rich-ass people together in one highly-concentrated place, even if all of them are working from home or taking Google busses to work, they're going to need services. Grocery stores, plumbers, babysitters, teachers, restaurant workers, you name it. Many of those sorts of jobs are not ones which are compatible with telecommuting--if my garbage man starts working from home, I'm going to be pissed!--and most of them are not of an income level which would allow a comfortable residence within the city where the job is. If you're making $30,000 a year as a teacher, spending $2,000 a month on a 400 sq ft studio apartment so you can walk or bike to work doesn't leave much left over for food and the like.
So inevitably, thousands upon thousands of workers need to commute various distances to keep their jobs and live in some level of comfort.
I realize that SF, as a peninsula, is a fairly unique scenario: it provides a high-value destination with severely constrained access points. Maybe not the actual logical conclusion of all similar circumstances, but a useful indicator of how things might play out in areas where money is aggregated into smaller and smaller groups who then take over relatively small and very desirable locations.