Return sales and customer reviews. Does no good to be a bad server if eventually you have no returning customers because of your attitude. The management certainly wouldnt have it if Jenny came in on her shift everyday on the rag.
I find it interesting that I did not express disapproval of the concept, but only questioned what maintained the link between service and remuneration.
I stated explicitly that I would gauge the success of the arrangement by the longer-term success of the business and the experience of the customers.