Assuming that's true (and it might be because other breeds are more common), would you also contend that pit bull attacks are no more serious than the attacks of other dog breeds?
I will grant that when pit bulls do attack, it is usually going to be more serious than with other dogs, but that is more related tot he fact that pit bulls are stronger with more powerful jaws than most other breeds and so naturally it follows that if there is a pit bull attack it is going to be more dangerous.