No, I think that's the default behavior but I believe I read somewhere that there's a way to stop zypp from reinstalling these packages.
Some of it is the internet again (especially pulling down things from git that are quite large), some of it is stuff that just fails during building
Do you know about chaotic-aur? It should solve most of your aur issues. There's no pulling or compiling. When a dependency is removed from the extra repo you wouldn't be able to install the chaotic-aur package until it's manually fixed but I don't think you'll have any issues updating already installed packages.