Barry
I am as embarrassed by my co-religionists as you are annoyed by them. I agree that some are aware of the problems they cause, but others are not (for a whole variety of reasons woo long to go into here). In these situations I have diffused situations where the CC were unable to get through to the passengers, the problems they were causing.
I can think of one situation of three young pregnent women each with a baby on their laps all on one row. Their husbands were on the row behind. It took a while for the penny to drop about the oxygen masks and as these people barely spoke English or Hebrew (they spoke Yiddish) it was down to a couple of us to explain the problem - at which point they moved immediately as requested.
There are many people like me on flights from the UK to Israel, people with a lot of flying experience and able to communicate with other less educated passengers. I assume other destinations cause similar problems?