Pam: "Perhaps there's a subtlety I'm not seeing. I would think that "plagiarism" is claiming something to be one's own original work that is in fact identical to, or derived from, someone else's work (even if that someone else is anonymous). "Folk process" would seem the applicable term whenever a person credits their source(s)."

It seems the answer would be very different for song-v-process. If one can document with reasonable certainly a song originating from the commercial/pop/art process, one can say the "folk process" itself is adulterated even without assigning a root cause.

Too, if widespread literacy, art, commerical print, &c are a criteria (absence thereof) the internet's modern folk process, if you will, is hard to wrap one's head around even without the legal issues.