I'm willing to bet that were anyone to have a million-selling hit record by overdubbing accompaniment onto trad singing, the singers' heirs and relatives would be only too happy to pocket the cash (even if they hated the music).

Someone mentioned Suzanne Vega above. That was the case there - Vega said she didn't think much of the dance track, but didn't seem to object to receiving royalties.

The same was the case with Moby.