Partially paid for by the cruise line? I would submit that it is the responsibility of the cruise line to pay their employees. As I said once before, I pay my employees. Period. There is never a line item on the invoices I send to my customers asking/demanding them to subsidize MY payroll obligation to MY employees.
Using the cruise line model, I would partially pay my employees then invoice my customers for some percentage of my payroll cost and expect them to "make up the difference". Pure nonsense. How would any normal rational thinking person feel if they received an invoice from a provider with an "employee gratuity" line item included? How many here would simply line through and ignore such silliness? I know I would.
@morpheusofthesea while you and I seem in nearly 100% agreement on our positions on most everything, I do have to quibble a bit with your use of the word compassion. I show compassion by acts and deeds along with contributions to worthy charities. A service provider is gainfully employed and is therefore never the recipient of our compassion. They are providing a service and if the service they provide is above and beyond, we show our appreciation by tipping individually.