Back to the issue of differences between the airport and cruise ship pick up locations. People from cruiise ships may not be hauling all of their luggage, but a lot of them have dive bags, and most are carrying shopping bags, back packs, purses etc...
I just think the luggage difference isn't a valid reason to not allow taxis at the airport, and I see no reason the airport would have to charge a fee. Some airports might do it, but not most, including Grand Cayman.
I know this is not a huge deal, but it is an issue that comes to mind every time I'm booking a trip or getting off the plane. I like having the freedom to choose what's best for my situation, without having some business or union step in and take choices away to protect their personal interests. I'm all about letting the free market and competition decide. And I'm more than willing to walk a block or two with my light luggage to protect that choice on principal.