Wow, this sounds a bit outrageous...

[kandrathe]

And hell, if you live in a big city, why drive at all, when public transportation or walking/biking is eminently more efficient and better for the environment?

Transit routes aren't always viable. If the distance you are traveling is greater than what you are willing to pedal (either effort or time), then it is not worth it. Putting it in an Atlanta context, say you lived in Marietta and worked in PeachTree City. A one hour drive, but an eternity by public transit and a 4-5 hour bike ride each way. You can tell people to work closer to where they live, or vice versa, but with the availability and pricing of jobs and housing it is not always possible to make a good match.