As @Otherbrother said, there would not have been any issue if they’d banned specific individuals who disobeyed crew member instructions. But it sounds like they failed to track who was who and ended up banning almost everybody.
That said, the behavior here is analogous to a plane full of American college kids headed to spring break in Cancun. While they might not all know each other or be “traveling together”, they probably all bought similar travel packages and many may even have been traveling on the same group plane ticket even if they didn’t know each other (there are travel agencies in the hasidic world who organize package tours for these pilgrimage events that are VERY similar to the spring break packages that American college kids buy).
And to @anon67050589’s point, I’m not sure that there would be any kind of fine if the exact same fact pattern was repeated with a bunch of American college kids all dressed alike getting banned when only a subset of them refused crew member instructions.
