I can see both sides of this. It would be very frustrating if it happen to me. I think somehow camera mfg. could help with this by writing to the EXIF data the camera se#. I know my camera does this. Then the photo finishers can have EXIF viewing software to view the SE# and you can have your camera with the SE#. Sure EXIF data can be changed, but it is some protection for the stores. Would be nice if this data could be embedded as write only. This of course would mean having your camera as proof, when you went to the photo-lab or having your SE# on file, so the photo lab could match them. I sure don't want to be in a pissing contest with a clerk with an agenda, so something is going to have to be done.