5% is huge. And the way app bundles work on macOS, tons and tons of disk space gets burned up for each application relative to on an OS like Linux distros, so each GB doesn't go as far in the first place.

It's also not the full extent of disk usage by built-in apps which aren't removable by normal means on macOS. An empty macOS installation is like 35 GB. NixOS is not known for being particularly space efficient, but 30-40 GB is how much space I use on it for the OS and all applications, including a ton of developer tools, on my graphical systems. For the base OS with a full fat desktop environment, most Linux distros have you looking at less than 10 GB. So this comes as a massive increase on an OS that already burns a ton of disk space before you even get to touch it.