It's even worse for developers.. sometimes you push out an app for internal or extenal test and it just.. sits there.. the users continue to see the old one. Or half of them get the new one and half get the old one, which makes no sense. This has been an issue for years with nothing but shrugs from google when you ask them about it.
OTOH with testflight you push out a build and 20 minutes later all testers get it, automatically, every time (I hate iOS development generally but that bit they got right).
At least part of the reason is software updates are so easy.. Tesla can do dozens of them without incurring any cost outside their normal development processes, so they do.
Another manufactuer may wait until there are several or just not issue some of the more minor ones at all, because each one is a dealer visit.