It happened to me a couple of times this year. It was really annoying to go make coffee, and come back to an updating screen. Even better, one of these failed and spent another 30 minutes rolling back the update.

I think you may be in a minority of people that intentionally turn their machine off at the end of the day.

I don't think I've intentionally shut down my desktop or laptop (excluding reboots and when leaving for travel) for years. Especially not laptops.

That makes sense, if you've got a laptop and you never reboot it then you're creating an impossible situation for the updater. I still don't understand the constant whinging in that case, though. Of course it's going to update while you're using it if, from its perspective, you are always using it.