Hypothetical scenario: a flight is filled with clinically obese people. As they all take up two seats, half of them don't get seats. If the airline is not allowed to charge them for the second seat, what then? Will they be allowed to tell the half that don't fit that they don't have a flight anymore, thereby losing half the income from the flight? On a low cost airline that should equate to a loss for that flight. Or, will they be forced to organize seats for the second half of the people on another flight, at own cost?