The primary reason is...the complete and utter nonsense drilled into the heads of CC by their CC management that....'somehow, we are all equal in the airplane, each has a say that is equal to everyone elses, and the Commander had no more authority that anyone else.'
I don't think it's as simple as that, 411A. There are undoubtedly SOME cabin crew trainers in the company that bring their own brand of bitterness and inflated sense of self importance to the classroom but there are also SOME flight crew trainers that appear to hold the belief that cabin crew should be seen and not heard. This then filters down through rank and file and from what I can tell, has done for so long, it's almost expected.
Going back to the mock up scenarios, I was involved as a "passenger" in one a couple of years ago that ended in evacuation. On the call to evacuate, the flight crew gave the call as per company SOPs, "Evacuate, Evacuate...Hazard on left!" At the initial words, "Evacuate, evacuate..." the crew were up and shouting instructions and as a result, both I and the Captain sat next to me only heard "Evacuate....Left" Even knowing the SOP's we both instinctively went to the left before correcting ourselves. On talking about it outside the mock up, the Captain agreed that passengers would probably also instinctively go to the left and that maybe it would be better for the SOP's to be amended to use only positive commands, such as "Right side only", in case part of the message was lost in the confusion. When we filed back into the mockup for the debrief, I raised this question very politely, pointing out that it was only on hearing it from the perspective of a passenger that the possible problem became apparent. I was given very short shrift by the flight crew trainer and basically told that that was the flight crew SOP and who was I to dare to question it. When I looked towards the Captain who had agreed with me, he suddenly appeared to lose the power of speech and gazed at the floor. If it had been the Captain raising the issue, would he have been dismissed quite as quickly?
Some airlines, however...have positively not allowed this nonsense to occur
Ironically, I would say that the airline involved in this incident is one of them, or at least it was when I worked there. Respect for rank and seniority was constantly drilled into us with no detriment to CRM. But it seems that that's not fashionable in these supposedly enlightened times where CRM seems to be perceived by many as "lets all get along and have a lovely time" rather than as effective communication between the cabin, the flight deck and the ground.