I'm in no way an expert at this sort of thing, but I understand that copyright law is really complex and companies find it safer to aggressively defend their properties rather than risk creating precedents that could become a liability in the future. I'm just saiyan. Edit: I don't know why I got so interested in this, but this page has a good bit of information and sources http://sites.lib.byu.edu/copyright/about-copyright/basics/