Environment variables, when used correctly, tend to work just about everywhere. That's why they're in use. It's the same reason why programs still install to `/

Environment variables, when used correctly, tend to work just about everywhere. That's why they're in use. It's the same reason why programs still install to `/usr/bin`, even though we're all very much aware that `/usr` is not "user direectories" and the whole idea of "userspace" vs "kernel space" is irrelevant in 99% of *nix installs these days (including containers).