Indeed, why should we even bother to count them? If twenty three kids go out on a trip and only twenty are on the coach home...well that's more tuck for everybody else?
Presumably they also had life-jackets too, which of course would make the counting of them, as opposed to their being abandoned to the waves, even more of a chore as they would be bobbing about for simply aeons...and there's crumpets for tea too.
Why they were there, I don't know, but better to be safe than sorry.
[any news on the amnesiac?]
Ignorance is bliss, bliss is happiness, I am happy...to draw your attention to the possible connectivity in the foregoing.