"But even that might be edited a bit." I guess so.

However, if a collector or curator can be sure that a song was learned from their collection can they also claim that their collection contains the authentic 'voice of the people'?

I can see if someone treks across a mountain range enduring floods and pestilence to come back with a gem of a recording they may then begrudge the whole world singing a song for free after it is played on the radio. But does Intellectual Property law give them any redress? There will surely be those who say the collector 'stole' it in the first place.