How is it?

How is it that I always get the slowest queue in the supermarket? This morning it looked promising until the man in front of me decided to withdraw his request for cashback and caused chaos with the till, ultimately spoiling the day of the Saturday assistant who had to deal with him.
Some people say that the queue you are in always appears to be the slowest because you notice the other queues moving beside you, and this is also true of traffic jams on the motorway. My wife obviously doesn't subscribe to this as she often shouts 'go into that lane' and 'go into the other lane'.