Not parent commenter, but the common argument is that for the class of service jobs where the employee's role is to interface with the customer and provide them

Not parent commenter, but the common argument is that for the class of service jobs where the employee's role is to interface with the customer and provide them a service, customers are in a better position to assess the employee's job performance than a manager. For that class of jobs, giving customers influence over the employee's "merit bonuses" is a more accurate system of rewarding performance and requires less managerial oversight to ensure good service. There seems to be some logic to that to me. Whether that justifies a reduction in the minimum base wage for tipped roles, etc. I think of as a separate question, but I don't see tipping as a structurally problematic norm as long as the job interacts with many customers and a significant portion of the population actually tips.