I kinda hope i'm wrong too! But I've also been around some business-ey people long enough to pickup some of the basics, and a lot of the times things seem counterintuitive.

Situations like this are kind of a game of psychological chicken between the company and the consumers.

If given the chance to buy something later, consumers will weigh the option upfront much less heavily compared to if they are "stuck with" what they buy. There's an implicit pressure to buy MORE than what you'll want from the factory, because a small increase in the total cost is marginal compared to the "loss" of not having a feature you want, it's a powerful tool used by marketing and sales to push people to a higher tier.

Without that pressure, anyone who's close to getting the extra package but not quite there just got a huge reason to not get it ("I can just add it whenever!"), and inevitably a large portion that think they want it up front won't end up wanting it.

(it sounds really scummy when written out like that, but literally every single company works like that. A huge portion of "business school" is going over this stuff from what I hear)

Tesla is actually a huge outlier already by allowing people to buy the FSD package after the first sale (that kind of thing is virtually unheard of in the automotive industry), but I think that has more to do with the fact that the "FSD package" isn't exactly feature complete yet, and the numbers work out better allowing people to slowly get pulled into the package over time as they add more features.