I noticed long ago that many songs that should have been labeled traditional get credited to the performer.... but as the hubby once said, all you need for a copyright is seven changes and a lawyer.

The copyright laws in the US have no interest in protecting public domain... in fact the opposite is true because the last thing in the world that the Disney Corp wants to see is losing their claim to Mickey Mouse, et al.   Copyright laws were originally to protect the rights of individuals... but corporations are now regarded as individuals and seem to have more rights than mere flesh & blood people. At least, so the Supreme Court seems to feel. Corps can't vote... but they can buy as many politicians as they please.