I used to be a copy editor.  Companies really have to protect their intellectual property (i.e. branding).  I would get complaints like, "in your description that the suspect was wearing "Levi's", unless it was verified that the suspect wore Levi(R) brand denim jeans..."

Paperclip, Aspirin, Eraser among many others were all name brands that lost their copyright protection and now can be used by anyone.