You're right, and it's a great monetising effort by Musk. You have to buy the full unicorn to get the EAP functions.I like how you call it the unicorn. TBH I don't really care about FSD, I'm happy to drive for myself, but I think EAP would come in handy on long monotonous motorway journeys.
My problem is, I'm not sure it's still available, even on the cars that could have had it, and there is no info on the net. I think of you have basic Autopilot, your only choice is "unicorn" 🦄