I'm not 100% convinced it's all that negligible, but in general I agree with your sentiment. Inefficient software updates are a pet peeve of mine. If I download 5GB of software patches I'd expect to see major differences after applying the patch, but most of the time these days it's barely noticeable changes, yet the patches are still huge.
Just look at the iOS 17 OTA packages for iPhone 14 Pro.
- 16.6.1 -> 17.0: 3.3GB - fair enough, new major version
- 17.0 -> 17.0.1: 452MB - security updates and bugfixes
- 17.0.1 -> 17.0.2: 384MB - security updates and bugfixes
- 17.0.2 -> 17.0.3: 450MB - security updates and bugfixes
- 17.0.3 -> 17.1: 1.35GB - this one is interesting, an update from 17.0.2 to 17.1 is actually about 150MB smaller than from the latest version which uses the same upgrade package as 17.0 GM
- 17.1 -> 17.1.1: 395MB - security updates and bugfixes
- 17.1.1 -> 17.1.2: 414MB - security updates and bugfixes
In total, I've downloaded about 3.44GB of updates for my iPhone since the iOS 17 upgrade in September, and have received WiFi AirDrop support, some security fixes, and better Home app Matter support. Security fixes are in general just a few lines of changed code, and should result in minimal changes to a binary, so if you just diff the new binary with the old one it should come out pretty minimal, yet the patches are several hundred megabytes.
Someone in a different thread suggested Apple were doing partial binary patching, but I don't see it.
There are so many low hanging enormous fruit to pick that it makes almost no sense to start with the very difficult and insignificant ones.