I’m OP, he runs Manjaro and I handle the updates whenever I see him, every month or so (I live out of state). I could do it over SSH but if something happens to break, it’s a pain to fix. I showed him how to do it in the GUI but he doesn’t care to do it.

What do you mean, automatically? Arch is a rolling release and I have to explicitly run pacman with the correct flags to update. At the same time Debian, which is not a rolling release, has the unattended upgrades feature which installs updates automatically.

But indeed, many things depend on the distro. For example, user-centric distros such as Elementary and others provide an easy to use GUI for updating the system.

And yes, Windows Updates was (is still? not a Win user) a nightmare.