My father loves to tell over a story he heard from Lenny Solomon, who basically is Shlock Rock. He said a lawyer for a famous musician ((I think it was Billy Joel or Elton John) wanted to begin legal action, or collect royalties (or whatever they're called) for the copyrighted songs Shlock Rock uses. The lawyer sat down with them and his first question was how many albums do you sell. When he heard the answer (it was a low number, be it hundreds or a few thousand) he got up, grabbed his stuff and left.
Obviously the details are a little fuzzy. The point is, almost no one sells enough Jewish music for anyone of note to care about their copyrighted music being used.