One factor is that then they wouldn't be able to sell as many copies of their exclusive edited edition. Which carries their copyright, due to the abomination that is the copyright system.
What makes you so sure that it's public domain? Of course the published forms that Mark Twain and his friends published should be public domain, but these seem to have been released in installments and other incomplete snippets. The full, raw manuscript, which seems to be what's requested, would naturally contain portions which were never published. Given that such a collection in its entirety would be a pseudonymous, unpublished work, the entire manuscript won't be in the public domain until 2031.
Since the copyright clause clearly states that copyright is allowed so that living authors are encouraged to create more work, it makes perfect sense that Twain's work from the 1900s will remain in copyright until 2031. This Twain guy is going to do a lot more writing before then.
Oh, my friend. If only it were that easy. A few years ago a short proto-science-fiction story by Twain was re-discovered and published... with a 2006 copyright. Photographers that make reproductions of famous old paintings can attach their own copyright. Etc.
Right, but the text itself (as Twain wrote it) is not copyrighted, only the text as set out in the published version. Which means that scanning the book and distributing a pdf of it would violate copyright, but anybody can edit and publish their own version.
Yes, but that's assuming that they publish the text as Twain wrote it. If they editorialize it enough they'll have produced an original work on top of Twain's work.
That'll carry their copyright, and since they keep the original under wraps there won't be a public domain version of it until the copyright of the edition now being published expires, or someone leaks the original.
