The problem is this isn't like cryptography where you can prove something. You can train a detector on a generator, or at least what you think the generator is,

The problem is this isn't like cryptography where you can prove something. You can train a detector on a generator, or at least what you think the generator is, but you can never know for sure. And any "likely fake" assessment can just be refuted by a sock puppet that vouches for the content.