People are dumb. You only have to look around at what other people are doing to see that the world is filled with dumb people. Take my trip in to work today. I saw at least 3 dumb people.
There was the woman who thought that even though the people getting off the train couldn't get the doors to open, if she kept hitting the door button often enough, eventually it would open.
Or the couple who parked their car in the road blocking it, whilst the wife got out. Of all the places they could have stopped, they picked the worst possible one. They could have driven on a few 10s of feet more and stopped in a proper parking space, but no - they had to block the traffic for several minutes. The wife even thought it was all highly amusing and grinned at the (probably) irate truck driver who her selfishness had caused to be delayed.