NPM is one big AUR, where anyone can submit arbitrary unverified code. The difference is that AUR is intentionally harder to use to prevent catastrophic one-line installs.

Is a "AUR" now just how we name unaudited software repositories?

Just to note, if we're talking about Linux Distributions. There's also COPR in Fedora, OBS for OpenSUSE (and a bunch of other stuff, OBS is awesome), Ubuntu has PPAs. And I am sure there's many more similar solutions.