I installed nix on my Mac but quickly backed out due to the complexity. I assumed the nix store would just be an ordinary directory with a tool for managing it, similar to brew. I discovered it creates a new Unix group, adds a separate APFS volume, installs a daemon. This was too invasive for a tool I was unsure if I even wanted to use, so I uninstalled it.
What is the reason for all this machinery? I went with the recommended multi-user install, should I have just used the single user mode instead?
It's because Nix wants to install into /nix. Once upon a time doing "sudo mkdir /nix" wasn't a problem, but recent macOS releases have made that very hard.
Nix could switch to an alternate location on macOS (e.g. /opt/nix) but that has a lot of downsides for interoperability with other systems.
Yikes, I had no idea. What a tough pill to swallow all because the directory nix runs out of is hardcoded.
It's not hardcoded, but you end can't take advantage of the binary caches if you change the directory. A company could certainly create their own binary cache and distribute that to it's users.