Seems to me you just stated that you do what you claim is done by other shops....? I would consider it "strange" for the owner of a company to determine whether or not the captain was helping or joking enough to warrant a fair tip without the divers input. Aren't your captains your employees and know what the shop policy and expectation is about how to treat customers? In your first paragraph you warn us about giving money to the owners, then in the second paragraph you tell us how your owner handles the tips...
Sounds like the people on your boats are liked trained monkeys working for tips, rather than dive professionals that appreciate a tip for excellent service. If your captains are not employees, then I could see how you never know what kind of service you'll be getting and have to make adjustments accordingly.
If I can smell that a service provider is just goofing for tips, I am far more reluctant to tip them than I would be a competent professional sincerely going the extra mile to make my experience more enjoyable. I've been on boats where it felt like the diving safety was secondary to the floating floor show, and I didn't appreciate it at all. This is not "open mike" night on a boat.
I have given tips to the owner of the op I use every time. In every instance, I have been asked how I would like that tip divided among the crew. I find it much more convenient to charge my tips at the end of the week rather than go to the ATM repeatedly to get enough pesos to cover everybody and carry it with me on each dive day.(I usually dive with a group of 4-7, so the tips are a pretty big part of our overall cost)