Even if it was a difficult operation to copy a song, it only takes one person to do it. After that the spread of the song via the Internet or other means of propagation is only limited by the honesty of the users.
“I found that when I went from Albany to Savannah, that I needed to put that white rice away, and I needed to turn that into Savannah red rice because they were big into that sausage, tomato-y, bell pepper-y rice mixture.”