The labels stand to gain more from this than they do trying to sue everybody. If they started suing people based on data from Apple, what would be the lesson to

The labels stand to gain more from this than they do trying to sue everybody. If they started suing people based on data from Apple, what would be the lesson to pirates? Don't pay for iTunes Match. D'oh! The aim of suing people is deterrence, but you don't want to deter people that have chosen to pay you, even you're making less money (say, per-track) than you would from a fully-legit customer.