Why does the other queue always move faster?

The answer

This is arithmetic. If each of three queues is equally likely to be the quickest, yours is the fastest only one time in three, so two times out of three another queue beats yours. It isn't bad luck, it's numbers. In this made-up case from Matter of Record Files, Inspector Fig picked a short, promising queue, and then the person in front produced a coupon, another coupon, and a very long receipt. The queue beside him moved and moved, and a man holding one banana went past him twice. When Fig switched queues, his new queue stopped and his old queue started racing. Queueing theory is the mathematical study of waiting lines.