Two things, mainly. They do a lot of the production steps in-house, as opposed to having a web of subcontractors (who have their own subcontractors)for each component. But the big thing is just efficiency of scale. Building and launching 100 rockets per year doesn’t cost 100 times more than one launch per year.

It reads like different people wrote different sections of it

Wouldn’t a centralized database/authentication server have been a simpler choice?

By far, which is why many people assumed that the plan was to start flogging NFTs later (once it became more difficult to back out).