Tesla has so many versions of "FSD" or Full Self Driving because they keep shifting the post for what exactly is Full Self Driving. What even is FSD compared t

Tesla has so many versions of "FSD" or Full Self Driving because they keep shifting the post for what exactly is Full Self Driving. What even is FSD compared to SD, where did the need to tack on "Full" come from? And I bet it's because of them calling their lane assist cruise "Autopilot" which implies self driving.