The prefix was there, and then it's not. I'm not sure why I couldn't call that being removed.

In none of the cases, the variable $x is imported

Importing is just writing in the glob slot from another package, which is what Exporter does (and it doesn't do anything else, the only special thing is that it is called implicitly, but you can call it explicitly and still have it work). The part that I missed on first read was the "from another package". Which means the variable is imported in the third case (edit: which is why the third one works).