However, most people wouldn't knowingly leave nude images of their spouse on the car's back seat when getting the car serviced. In many ways this is similar.
Edit: For people who think I'm blaming the victim, I am not. I thought that was clear, since I blamed the thief/poster of the photos! This is in many ways similar to leaving photos in a car. That is not to say that the person with the phone is at fault, but that this also happens in many other cases. If this happened to me (which it has), I'd do something else instead of sending my phone for repair by an unknown person.