There's actually a bit more to it than that. A lot of what Apple apps actually do is hidden in frameworks made for that one specific app, which, unlike with 3rd-party applications, are part of the system, not of the app itself.
Compare the size of Safari.app versus Safari Technology Preview.app (which actually ships all the frameworks it needs).
If you have those apps handy and could share the sizes it would be very useful. I don’t have a way to check this. (Or do I? All I have is an iPhone )
I don't think that Safari should be used for comparison here since web views have a special place in the OS. Which of the other stock apps have a similar architecture?
Reminds me of when people were clamoring for the ability to delete 1P apps to save space
Sounds like how Internet Explorer used to be integrated in Windows. That was quite contentious at the time!