What you're selling is minutes of entertainment. Or, if you're running a pub, number of pints consumed. An act--single, duo, trio or entire choir--gets paid on the basis of how they provide what you're selling.
Which is, I realize, a strong argument for going solo.
   It's more fun playing and performing with others, but it's not realistic to ask the one who pays the pipers (or pickers or whatever) to pay for that fun.