What is it with people and queues. I was stood in a queue to use a cashpoint and there were at least 6 people in front of me and one at the machine. When the person at the machine finished 5 out of the 6 people in front of me moved as a group to the cash machine to watch and wait for their friend to get some money out.
In supermarkets it is the same. You can often see 3 people queuing behind their friend or relative who is buying something.
I genuinely believe if you stand still long enough but look as if you are waiting for something then a queue will start to form behind you.