That was my point. If I buy a van that drives itself I can tolerate much longer commutes - I'll just put a bed in the back and sleep my way to work. So what if it takes three hours.
Incidentally, I was talking with a government transportation engineer recently, and that's what keeps them up at night - trips that are too long or just too inconvenient today become doable with self driving cars.
Does this effect overcome the added amount of cars on the road from people who can now drive that wouldn't be able to before? I'm skeptical.