The problem with any of these numbers is the limited usefulness of them. If I load up an aluminum skiff with 3 bench seats and it's placarded for say 3 or 4 people, that's all well and good but if all of them stand on the transom and there's an OB on there as well, it's going to swamp and sink, even in calm water. The layman wants information that is obvious and foolproof, and there's no such thing here.
If I load my 32 footer with 8 people, they can mostly move around where they want other than the flybridge or the swim platform and nothing is going to break and I'm certainly not going to roll over. Putting 27 people on there would like loading up that skiff - possibly OK, but those people better all know to keep the boat balanced or at least sit where I tell them and not move unless I clear it no matter what happens. Otherwise results are unpredictable.