The pass mark for my company for cabin Crew Exams, EP's etc is 80%. I know in my job I don't know everything, but I am aware that I don't.
As far as people not been able to operate the exits. Natural selection kicks in. I'm looking after number one. Help people after that. If people don't realise the importance of their responsibilities and the potential of their environment so be it.
My ex-partner was on a plane and an old lady didn't know how to undo her seat belt when the sign was turned off at the gate. My ex was never backwards from coming forwards and let her know infront of everyone that she had failed to listen and understand the emergency brief and put her life and others around her (potentially blocking the exit row). The old lady was very emabrrassed. Let's face it other than aircraft how many belts these days require the lifting of the buckle? Everything these days are clip in and button to release types. Twenty years ago in the Ford Valiant maybe but not today.