> Elon Musk said it might be because they “still don’t believe it’s real.”
That's because Musk has been lying about the state of full self-driving for years. False claims, staged videos, and continuous lies of "next year, for sure!" aren't a good way to go:
https://www.reuters.com/technology/tesla-video-promoting-sel...
In 2016 Tesla claimed "that, as of today, all Tesla vehicles produced in our factory – including Model 3 – will have the hardware needed for full self-driving capability at a safety level substantially greater than that of a human driver". That was a lie:
https://www.tesla.com/blog/all-tesla-cars-being-produced-now...
Lying is part of the company culture at Tesla.