In practice, lead times are long enough and release cycles short enough that it can make sense to have these devices at point of manufacture so you can ship with the latest software image.
Imagine you order 10,000 pre-flashed SD cards for your project but half way through the production run you decide you need to change the software. Do you discard thousands of SD cards and re-order a new batch? Or do you buy a couple of these and simply add it as another station on the assembly line so you can get back to production right away?
No, you don't pull a run of hardware mid-run to rev their firmware unless there is an absolute shitstorm which would also just be handled by the manufacturing process i.e. why would you ship the "bad" cards to your office or some such scenario rather than run them again through the same at-scale manufacturing process?
Anyways, as somebody already pointed out, the vast majority of these cases would be handled by live updates.
Then again, if I was wanting to burn 1000s of cards a day, I would probably do what everybody else does and create/contract an actual manufacturing process. This seems to fall in the niche between somebody that just happens to flash a lot of images and businesses at scale that do 1000s and it seems like it's a bit of a perilous position.