Fingerprints can change as you age due to accident, mutilation or skin disease, so does your iris they use for scanners
Shadows is only one form of comparing. Triangulation is another used by computer software, but is easy to do manually, and works easily on these 2 pics. Ratios is another, and the two pics here are different sizes so it needs to be taken into account. Simple measurements are another one the ratio is known. You can also use pure maths The pics are the same person. Be bothered to learn the the above techniques and you'll discover your initial assumptions that it isn's are incorrect.
One of the problems with peoples beliefs is that they can't betaking the time to educate themselves so they can understand what they believe is actually correct or not. In most cases, people take the easy route and just continue to go with their initial view which is the lazy way.
Google's Picasa digital image organizer has a basic comparision technique built in.![]()