At the fly in at Concrete last year, I was looking up the runway at approaching planes.  There are designated crossing points for the runway but people are able to cross elsewhere if they like.  I saw a guy with canes heading towards the runway.  He was not moving fast so I figured he would wait for the landing aircraft.  He kept moving but I was sure he would check whether it was safe to go.  Nope, he just kept on going while a plane was on short final.  At some point he must have realized that crossing a runway can come with some peril and he suddenly started moving a bit faster – not fast, but at least faster.  Meanwhile, the pilot on approach either didn’t see him or decided he would miss him so didn’t go around.  The whole thing was one of those that you witness with a little incredulity.