Random Thought about Tuna Cans!!

Ok people, so I have been working out and eating a lot of protein, but just had a thought.. Please reply with yours.  Why are there some tuna cans you can buy that have a pull top or soup that has a pull top, and others don't?  Why not just make them all pull tops?? Is this some type of conspiracy with the can opener companies?? I am baffled.. Post your thoughts!