This reminds me of that spider jpeg someone tried to pay a bill with a while back. How do you know that the mp3 has actually been deleted from the user's compu

This reminds me of that spider jpeg someone tried to pay a bill with a while back. How do you know that the mp3 has actually been deleted from the user's computer? Other than heavy-handed DRM, I don't see how that would be possible. For some reason, I don't the the problem with the online music market today is lack of DRM.