Total BS. First of all, the next U2 will be an original music band, like U2, not a cover band. Therefore, no royalties are due anyone. Second, you could charge a cover, and let the band succeed or fail on their own ability to draw, which would cost you nothing. You're whole argument is total fiction.
Answer this question:
If the next U2, like the real U2, came to your bar and played a set of all original music, how much do you owe ASCAP and BMI as a result?
the next U2 (IMHO) is playing at my bar and they play a mix of cover and orginal. A bar band MUST play cover, the customers DEMAND to hear music they know and like.
And if the band happens to do a cover of a commercial song? Nah. Couldn't take that chance. Better they don't play at all.