This makes no sense to me at all. The bus leaves when it is done unloading and loading. There is no question of fairness here, it is not like someone made the f

This makes no sense to me at all. The bus leaves when it is done unloading and loading. There is no question of fairness here, it is not like someone made the fries you were waiting for and gave them to the wrong person. In a network metaphor, you do not halt all other TCP connection on a system because one TCP connection was stalled by a lost packet, in the name of fairness. No one would ever want that. The people on the full bus can easily see that they are not moving because they are still unloading. Who would see another empty bus passing by and thinking "those people should be made to wait"? In my experience on the subway, a train will start SKIPPING STATIONS when they are bunched together, forcing me to get off and wait for another train entirely. So I don't think fairness is the reasons buses keep their order.