I think I can explain for you:i have so many friends with automatic updates on but they are on older software. i dont understand why
Definition:
Automatic Updates does not equal “immediately update upon availability”.
Apple will push the update to your device and the device needs to be in a state conducive to updating (storage, power, WiFi, not in use)
The terminology they use might also be relevant:
iOS 18 to iOS 26 = Upgrade
iOS 18.0 to iOS 18.1 = Update