More than that, you need a grand conspiracy that is so obscure third party observers can't see it happening. Relatively easy with software, because software is

More than that, you need a grand conspiracy that is so obscure third party observers can't see it happening. Relatively easy with software, because software is obscure almost by definition. Difficult with something tactile like paper ballots. (Or you need a country where those third party observers are already powerless, but that's beside the point).