Assuming they have a laser printer, photoshop skills/subscription and know about acetate sheets. I'm willing to bet most phone snatchers don't even have one of those ingredients.
Most phone snatchers aren't after the information on the phone. The point is not that this would not be a targeted attack (it would be), but that it might not require a particular combination of circumstances or set-up to follow one around and snap just-the-right-angle photo.