What is wrong with a broom?

There is a guy outside my office with a leaf-blower. The ground is wet because it is a) England, and b) late September. Leaf-blowers do not work on wet leaves that are stuck to the ground. How do I know this, you may ask, as I do not own and have never used a leaf-blower. I know this because he has been going over the same patch of car-park outside my window for the last three-quarters of an hour. What's wrong with a regular broom?