First a history lesson. Copyright laws came into being in the mid 1500's as a result of the invention of the printing press. Then as now, the argument could be summarised as follows. If a creator can not earn an economic return, they will be forced to stop creating. For years illustrators have used photographs as reference material for objects or creatures that they have never seen.
Photographers thumb through magazines looking for new approaches and ideas.
This is valid. Culturally we are the visual sum of all we have ever seen. My work is influenced by cave drawings, Rembrandt and Degas. But here also lies the ethical question. If you are an illustrator who needs to paint an aardvark, you might seek out ten photos of aardvarks to see what the animal looks like.