Wal-Mart is afraid that people might be trying to print copyrighted photos without permission. This restriction has caused many amateur photographers to have lots of trouble getting their shots printed. For example, a man who wanted photos of his mother for her funeral couldn't get them printed because Wal-Mart thought that they were taken by a pro.
This is a ridiculous policy, how can they judge which photos are pro or not. I guess it comes down to this: If you take good photos, don't take them to Wal-Mart.
Read (Via Boing Boing)