So the government allows the airlines to charge surcharges on fuel for every single ticket and then if a passenger ask for a "same day" flight change, a huge penlaty $$$ is imposed otherwise the airline would rather fly with empty seats!!  Why not, in same way we consumers pay a surcharge, the airlines should return the surcharge in form of a penalty tax for every empty seat on their flights; We are giving a free ride to their greed on each and every flight with empty seats.  A "financial incentive would make the airlines willing to fill those empty seats very quickly, without charging the consumers, exactly in the same way they do when they are overbooked!!