You would think, but you would be wrong. It wasn't that long ago that someone rented someone the name of a licenced permitted boat so it could dive in the park. Just paint the name one it...
That boat isn't, er, around anymore...
What would stop an op from putting the name and number of a permitted boat on it? Especially if that boat was a similar style. Just avoid having your boat around others who might take notice.
What would stop an op with a permitted boat from putting the same name and number on other boats? Just make sure they are never in the same place at the same time.
From a tourist perspective, that list of licensed boats is not a great way for me to identify illegal ops. For one, it doesn't say what op owns what boat. In some cases, it is obvious. If I book an op I don't necessarily know the names of all their boats. When I show at the dock is when I find out the name of the boat I'll be on and no one has ever told me in advance and guaranteed I'd be on a certain boat. And finally, even if I carried this list with me and checked it before stepping on the boat, I'm not going to make any accusations since I don't know if the list is 100% up to date.
How about a list of these alleged 100 illegal ops? If there are any prominent names that are operating illegal boats, name them.