But then you'd just see increased fares as a result.

Oh. Wait. I forgot...airlines these days don't seem to know how to charge customers what it actually costs to fly a plane.

Seriously, though, I think that's too simplistic an idea due to the fact that tarmac delays are often not caused by the airline itself. The carrier will essentially be penalized for being stuck on the ground when weather strikes, when there is congestion due to over-scheduled airports and/or outdated ATC systems, etc, etc. Airlines already lose money when there are delays, when crews and planes and passengers must be reshuffled, and so on and so forth.