People are generally willing to follow the rules and behave in a civilized manner if:
They can trust that the rules will be enforced, and
The rules are clear.
Neither of these conditions are met and this is primarily due to a failure or inability of the airlines to maintain order.
It used to be that our society as a whole had an ethos that did not require such reinforcement but alas, those days are gone. It seems to still apply in Australia (in the airport) but few other places I have been.