... and glare at you because you start queuing for an individual machine.
Because they're afraid that the other queue might move faster and they don't want to look silly? How long does it take to use a cashpoint anyway - 2 minutes at the most?
And then it all breaks down when one of the machines is different from the others and people only want to queue for that one.
Single queue starters - get a life! If having a single queue was possible, the bank would do it.