One way I see this unfolding is, like was said, an instructor was leading a group of buddied-up divers. One of the brand new divers lost their buddy, but since everybody looks the same to a brand new diver (and to a lot of experienced divers for that matter),the buddy latched on to another "diver in a wetsuit" and thought that was their buddy. At one point the instructor stops to assess, realizes there's an odd number, tries to figure out who's who and can't, asks everyone to make a safe ascent and at that point the buddy who lost their buddy realizes of it. It gets relayed to the media as a "headcount" when in reality there was more to the story than that
Precisely. Which is why the responsibility of the instructor is so much higher in poor conditions, and why it is important that (s)he takes whatever steps are needed, including the use of certified assistants and/or reduction in class numbers, to ensure (s)he maintains control. It is not acceptable for an instructor to plead that he couldn't see so lost a diver.
And of course we're not talking about "brand new divers". We're talking about unqualified students, who depend utterly on the skills of their instructor.
Personally, it seems to me that something like this could happen to any instructor, no matter how good you are. But then again, I'm not an instructor so ....
Something like this should NEVER happen to an instructor (though it does all too often, even in quite benign conditions). I am an instructor and have taught many students in cold dark opaque British waters. I have never lost a student, because I regard that as a key requirement of my job.