In physics, a force is said to do work if, when acting, there is a displacement of the point of application in the direction of the force. For example, when a ball is held above the ground and then dropped, the work done on the ball as it falls is equal to the weight of the ball (a force) multiplied by the distance to the ground (a displacement).  "The weight of the ball"  When that damn airplane wants to get from A to B, it is the weight just as much as the distance that accounts for the work, and the work is what is paid for in dollars.  Assuming you are average or under you are paying more to subsidize all of the fatties.  If you are a fatty, your ticket was just discounted by all of the humans on flight