@holymoly The US cellular system is completely different than other countries. In the US, Samsung releases the builds to the carriers.
- For carrier locked devices, each carrier adds their special sauce to the build to make it unique.
- For unlocked devices, each carrier adds the needed network information.
- Each carrier then carries out their test suite to ensure that the release won't break their network. There is no guarantee that carriers test the unlocked and locked versions at the same time.
- When the carrier is satisfied (and sometimes they aren't), they releases the builds to the public.
@Leify "Unlocked phones are at the mercy of the carriers in the US because they have to wait on all of them first."
Every carrier can test and release updates to unlocked devices on their network regardless of what other carriers are doing. Historically, you will frequently see unlocked devices on AT&T getting updates long before the unlocked devices on T-Mobile get the updates.