//Our pupils were happy to be caring of each other and it taught them how to behave well in the wider world.//
Of course they were. But you’re missing my point. A person such as the child in the aircraft cannot rely on decent behaviour from all those around them all of the time. If you can tell me, hand on heart, that all – absolutely all - of your former pupils were as loving and caring as you taught them to be all of the time, I would be very surprised (and they would be a very unusual group of children). As well as that, not all schools, and not all teachers are as successful as you obviously were in instilling those qualities in their charges. In short, with the best will in the world, there will be “wrong ‘uns” out and about (as the OP’s story shows). That’s why a level of personal (or parental) responsibility is required.
// I think perhaps New Judge is either quite young or has led a bit of a charmed life,…//
I’m neither. This is not about sympathy. It’s about pragmatism. The last question posed was what should the girl and her classmates do in school. Bearing in mind the above, she or her parents need to take responsibility for her safety and not rely on everybody else around her behaving responsibly. Hence my suggestion.
//If this was actually NJ's daughter or granddaughter, for example, I wonder if his attitude would be the same by the time she reached 14 years old.//
It would be precisely the same. I would instil in her that she cannot depend on those around her behaving well enough all of the time to avoid her problem. To be anything otherwise would be irresponsible. Throughout this thread there has been a Utopian (but naïve) aura of “We’ll explain to everybody how to behave well and it will all be OK.” Well sometimes they don’t, and then it won’t.