I think that the reasoning is more along these lines:
1). If you cant afford to drive as much, then you can look for a job closer to home. This doesnt mean you drop everything right now and quit your current job, it means you prepare for the oppurtunity of getting a different job if it comes along. Be ready to take advantage when the situation presents itself. Who wouldnt like to work under 5 miles from home and spend less time commuting? Maybe the new job pays less, but you have to factor in less gas, less wear and tear on your car, less time spent in the car.

2)If you can afford all the gas you want, then you probably arent worried about where you job is. If you can afford gas, but still want to work closer to home, see #1.