He is right that LIFO (last in first out) queue is more efficient when there's more demand than queue throughout. But the fairness isn't just a problem with the

He is right that LIFO (last in first out) queue is more efficient when there's more demand than queue throughout. But the fairness isn't just a problem with the sense of justice. As indicated, with a fixed timeout, LIFO will cause more spurious timeouts when FIFO wouldn't. The best of all worlds, if the speed of light or transition between different queues isn't an issue, is to have a centralized queue management forming a super queue. Some stores do this already, creating a single queue that dispatches shoppers to a checkout counter. Doing this cuts down the average wait time, and makes people "give up" more willingly under heavy load, since the queue would look much longer.