When we talk about the "exclusive" nature of this DLC within the NSP package, we are referring to assets and features that do not exist in the base 1.0 version of the game. Here is what you get exclusively via the BCP:
Why do people specifically search for the term? Because unlike the base game, which is readily available on cartridges, the Booster Course Pass cannot be shared physically. If you buy a used copy of Mario Kart 8 Deluxe at GameStop, the DLC is locked to the original owner’s Nintendo Account. mariokart8deluxenspboostercoursepassdlc exclusive