They‘re listed on the App Store but they‘re fake listings. Removing a core app from the home screen does not remove it from the device. Installing it from the App Store restores that link.

That means updates still need to be a part of a system update.

In iOS 10, reinstalling the News or Calculator apps was instant. In iOS 11, the App Store list sizes for these apps, and reinstalling them takes a few seconds (on my phone and connection).

I haven’t measured data usage, but I suspect this means that removing Calculator’s icon actually removes its code from the system. If that is true, it is potentially upgradeable independent of the iOS system, at least from a technical perspective.

I suspect Apple’s QA and release processes cannot take advantage of this, though.

How this works in Android for system apps: One can only disable a system app. This disable button replaces the uninstall button. It deletes any updates to the app from your phone, since it will obviously still have the original version baked into the ROM, and removes it from the app list. It might also disable any service registrations for the app... Unsure on whether that's true.

Re-enabling the app will basically restore the ROM version. You can then install updates from the store, which I think is basically a full install and the ROM version is ignored again, based on the consumed space of such apps.

That's interesting! I hadn't noticed the change. As you say, it's probably not relevant until Apple can actually release a single-app update through that channel, but it might be a glimpse at a future where that's an option.

Like IE in Win XP

You are probably correct. Maybe if the developers decided that their precious prefab apps didn't need to come prebaked into every release of android and iOS and instead let the consumer pick, the market would be a bit less full of app bloat.