BMI, ASCAP, and SESAC receive literally hundreds of millions of dollars on behalf others and are responsible for collecting it, holding it, and distributing it, without regulation or oversight of any kind. Each handles it in very different ways, so different that the amount of money an artist receives from each is completely different.

I ran across a writing team, one of whom belonged to ASCAP, the other to BMI--one received twice as much money in royalty payments as the other, for the same song!