Fair enough. Saving Sinjin Edda depended a great deal on the planet having gross cultural features that no society on Earth has ever had. Because of obstacles the PCs had to overcome, and because of things that the villain had to work around to effect her plan, and because of the legal and cultural peculiarity that she exploited to become one of the richest people in the universe despite the PCs shooting and capturing her, that story could not have been told in any contemporary or historical setting. SF hard-liners don’t have any respect for economics and sociology, but I don’t mind that adventure being classified as “soft sci-fi” by a hard-SF purist.
So as not to derail this thread, I shall continue discussion of Saving Sinjin Edda in a separate thread devoted to that adventure.