"Papers by themselves aren’t licensed".  Not true.  Post Berne convention, any copyrightable work is copyrighted by default, and you cannot reproduce it without a license of some kind. (excepting some special cases like works of the US Federal government)  Papers often do specify licensing (unless they're all-rights-reserved: in which case you're just getting no license), specifying licensing is a universal requirement in academic publication (though sometimes you're not given a choice, you're just forced to assign copyright to the publisher or likewise).

"Open source documentation is also not copyrighted if it is given away in an open source license."  All licensed open source works are copyrighted.  The license permits you to do all sorts of stuff (if its an open source license), but it's still copyrighted and some rights are usually reserved (for example, even the most permissive licenses don't generally allow you to falsify attribution or strip licensing info).