Shore excursions booked through the ship are already WAY over priced , no way would I tip . A private tour may be different, I would play that one by ear. Th e purpose of tips has been bent over the years, why should I make up for an employers unwillingness to pay a proper wage. I tip my steward and waiter because they do earn it ,I always have felt that the services on a ship are far superior to a land based vacation.
I do not tip owners . Period. The cost of your meal is based on several factors, the food costs, the staff costs, and the cost of running and maintaining the actual restaurant. Since by serving themselves their staffing costs are reduced( there still may be kitchen staff) they are making abetter profit line then if they had to pay a waitperson a wage.
Also a hair dresser usaully works for 30% to 55% commision depending on the area and the price for products, so if the owner does your hair they get it all.( I realize they have costs too, but still they would come out ahead of an employee.
All things having been said I still would make exceptions, years ago we used to go to a small restaurant that was struggling to survive, we liked it and wanted it to" make it" so we did tip the owner who was serving us as well as working in the kitchen.!