I think we’ve discussed this quite a few times now. It’s because Nine only use the WWOS watermark for their own produced/input coverage. These other events are just a program delivered to Nine with no input from them (i.e. are not "another presentation from Nine’s Wide World of Sports), so they don’t want to brand it under their WWOS branding. They are the only network that have a specific watermark for a brand, so they are different to the other networks who just use a variant of their normal watermark/logo for sports broadcasts.