It happened to me last year but it was no bother to walk 100 yards back to the office where other patients can be driving 40 miles and then can't find a parking space.
I remember asking the receptionist at the RSCH eye clinic some years ago (After had a particularly hard time finding somewhere to park) "Just how many patients DNA simply because they cannot find a parking spot and have to go home again?" The shifty look and under breath mumbling suggested to me that the answer was "Quite a Lot actually!"