We've gone over this before here at MC - but it is worth discussing again.

In the US, the practice is meant to collect royalties that are paid to publishing members of the organizations. They demand payment from all public places that play music; jukebox, TV, radio and live music - and they base the rate they demand based upon the seating capacity.

ASCAP, BMI and SESAC pay their royalties based upon sampling of music on the public airwaves, web, TV and presumably live performance. The funds they collect is meant to reimburse the composer/publisher for his license fee.

I don't know anything about the rates. I know some small venues decline to make the payments and choose forgo live performance. Fair enough. Assuming the rates are reasonable, the practice is like any other tax or license fee.