The explanation I was given(and this well could be bullshit) was that they’re “sold”, in the sense that they’re claimed by a lot who will further sell them on, hence the storage on-property until they’re transported down the line.

Which is a very real thing for a typical auto manufacturer. Tesla, however, doesn't have any kind of third-party dealer network. They control the entire process all the way to the end-user.

Some are also held and leased for employee use, be it through employer vehicle loan or a leasing program like VW had, where you could select from a variety of models owned for the company fleet(including other manufacturers under their umbrella, like Audi) for up to a year.

This could be possible, not sure how Tesla operates.