This I do not understand, most of the people who run these excursions are the owners of these operations. I have never heard of tipping a restaurant owner, or the owner of a hair salon, only the people who are employed by that entity.
For example, if I book an excursion with Peat Taylor in Jamaica, and he is the one driving, then why does he deserve a tip. He chooses to drive so that more money can go in his pocket, as opposed to hiring a driver to the the driving for him, and paying him/her a share of the per person fee.
I am all for tipping employees of these excursion companies, but I would never tip the owner.