Passengers
I try not to post here because I have no flying qualifications whatsoever. I do understand a bit about how people learn things. The safety briefing has absolutely no context for a passenger. "In the event of cabin depressurisation" is a completely meaningless phrase to most passengers.
So we are told how to respond to something we don't understand.
The idea that a short talk at the start of a flight would lead to perfect compliance in the event of an incident which makes ordinary people fear for their lives is simply wrong.
There is much talk here of passengers not displaying common sense in an 'emergency' - see the Munich Fire thread nearby - but frankly, if you think that a short talk and a look at the safety card means people will understand how to behave in an incredibly stressful situation, then, politely, you are not displaying common sense.
The challenge is to manage the passengers inevitable lack of understanding.