No-Auteurs films? Or is there always an auteur for each film?

In many cases it is really difficult to design who is the « auteur » of a film. During the history of film we can choose many examples. When films were sold, each owner of a copy could change it. When multiple versions were popular, in the 1930s, who was the auteur? Other examples tell us that each projection could be unique and that the meaning of a film could be different from one movie theatre to another one.