[mellavora]

your observation is correct, but perhaps not the conclusion? If more people are traveling over a given section of road per hour (as you imply), isn't that more "efficient"?

[ajuc]

The alternative is public transport or living closer to your work, both more efficient than everybody driving in their cars and waiting in the trafic.

Basically it's comfort vs efficiency, and people maximize their comfort within the acceptable traffic jams level.