I don't think David is saying his wife is the photographer. If I am understanding correctly, he is saying that his wife would be receiving a bunch of photos from a customer, scanning them into a digital format, and then burning them onto a CD.
If the customer had photographs taken by someone else (i.e. professional prints from a photography studio), then the customer would not have the rights to those photos and be able to give permission to reproduce them onto a photo CD. Permission would have to be received from the original photographer before doing anything with the photos. Just because someone purchases prints from a photographer, doesn't mean they also obtain the copyright for those prints.