I voted for 'My fault', but in reality it is the fault of all the people in the pictures.
Always stopping when they should go. Always turning the wrong way, stepping out of symmetry, stepping out of the light. Parking in front of my tripod. Waiting politely outside of my shot when I want them in it. Asking me stupid questions just as the light is turning. Doing something really boring after doing something really interesting.
It just drives my crazy. Get with it everyone!
Edit: Asking me if it is ok to park in my shot, because they mistook my camera for a ticket machine, and they think I am the traffic police. GO PARK IN THE RIVER! Sheesh....