I picked up Criterion's new DVD of one of my favorite movies, almost literally since I first got interested in old movies, Max Ophuls' Madame De....
One of the extras is an interview with one of the writers of the film, Annette Wademant, and that reminded me about a difference between writing credits in American films and writing credits in the films of many other countries. Basically, the American system is set up to give credit to as few people as possible; it takes a lot of wheeling and dealing and sometimes full-on arbitration to get a writing credit on a U.S. film.
The rules in some other countries seem to have been less strict, and in France, where Madame De... was made, movies would have separate credits for "Scenario" (working out the story) and "dialogue" (the written script). On Madame De..., Ophuls and Wademant share scenario credit with playwright Marcel Achard, but Achard is credited as the sole dialogue writer. If this had been an American film, Achard would almost certainly have gotten sole credit and there is certainly no way Ophuls would have gotten a writing credit on the film; from Wademant's description of the working methods, he led the story conferences and mainly did what every strong director does to work on the script, whether or not he gets credit.
There's no conclusion here, just that the different systems for writing credits tend to give the impression that almost no American directors worked on their own scripts, whereas most non-American directors did work on their own scripts (or in the case of Ophuls, that he was a writer-director in France but not in America), and that's probably an over-simplification.
(Also, why does every release of the film refer to it as The Earrings of Madame De... when that is not the title that appears onscreen? I understand why they added "The Earrings" on posters, to make it clearer to foreign audiences what the movie was about; but I don't know why the mis-titling is still perpetuated.)