The musician DOES pay fees, just like the customers who buy drinks there. It's called shifting costs, and it's basic economics. If the bar didn't have to pay fees to have songs played in their venue, then the musicians could be paid a little more andthe drinks and food could be a little cheaper. It's the same as when an employer pays half of an employee's SS; the employee would be a fool if he thought that it didn't affect his bottom line too.
And if you never make money playing live music, that's your problem. Nobody is forcing you to do it.
Then you're an idiot for booking them.