Park and Run?

I had a good idea the other day.  A parking garage 5k. The race would start at the entrance to the garage and end on the top floor.  Spectators could witness the whole race without moving a step, and there would be no threat of rain cancelations.  The route sure would be easy to mark, etc.  The difficulty factor would draw weekend warriors from far and wide.

I looked online, and ... no one has done this yet.  Surprise!  Are they crazy, or am I?