Originally Posted by Aquaticus

You have low cost carriers filling 150-200 seat airplanes out of the same markets where Ual, Aal, and Dal run 50 seaters. Airlines now make more money off of ancillary expenses like extra legroom, seat selection, credit card signups, buy on board, etc that makes high volume sales more profitable then charging more for only 50 seats. They also see more volume for connecting passengers and much easier recovery when the plane breaks or weather hits. If you have 300 Airbus you can find a spare or shuffle another flight to cover the open segment and have crews all over the country to pick up the pieces after weather.