Social structure and efficiency 

Boarding airplanes must be the most inefficient process. The first class passengers, those who sit at the very front, board first. Then the middle rows. Those who sit at the very back will board last. With more and more front rows filled, the back rowers struggle to get through the narrow aisle, bumping their carry on bags against the seats and the sitting passengers, and negotiating their passage with standing passengers fondling their stuff on overhead storage. Boarding is a slow and painful process.

It would be much more efficient to let the back rowers board first. There will be much less struggle going through the aisle. The whole boarding process will be much easier and much faster. But this is not how airlines operate. 

Airlines choose the most inefficient way to board the planes, the slowest and the most painful way to board. By inflicting greatest pain to the back rowers, they demonstrate the high value of the front rowers, the first class and business class passengers. This is the way to maximize ticket prices. 

Airlines are not the only ones to maximize profits by structuring social activities in the most inefficient and painful way. This is a general rule in the society.