Fact is everything that makes a cruise or cruise line from the telephone representatives to the President and board of directors is PAID WITH THE FARES COLLECTED FROM THE PASSENGERS.
And just like any other service I pay for I understand that even those flipping the burgers, who I actually and indirectly pay, are to a degree my employees and deserve a living wage that most probably should rise with inflation.
I don't wish to debate who is and isn't an employer, in my opinion it is a person who pays someone or a group of people to provide that person with goods or services. So, YES, the passenger is the ultimate employer of a series of employees.
Tipping in the American culture IS PART OF LIFE and is and has been for decades considered a part of an EMPLOYEE'S salary (EVEN BY THE IRS.).
I don't really care who tips or doesn't, but I worked in the service industry and did rely on tips just as the employees on cruise ships do. I also UNDERSTAND that there is such a thing as inflation as is easily seen by the increase in cruise fares over the years.