You're ignoring qualitative differences and other costs. Commuting to work in your own car, which lets you keep that demo system handy that you're going to show a customer, and lets you pick up groceries on the way home, has a higher value to most people. It also means you get somewhere faster, and on your own schedule. If you add up all the hours that smart engineers would otherwise be sitting waiting for a bus, that has a cost to society as well.

The difference between a car and a bus to me is the difference between the internet and cable television. With the former, you get what you want when you want it. With the latter, you have to go along with the group and rely on others to decide for you.