Pushing Buttons

Why is it that when you are standing at the elevator someone has to walk up and push the button AGAIN!

Did they think you were just standing there for the pure joy of looking at a stainless steel door? H E L L O!

The other thing that annoys me is when you get to the bottom floor and there is someone clamoring to get ON before you've even had the chance to get off....it's an elevator people, as long as there is someone standing in the doorway it's not gonna go anywhere.