Come to think of it I don't recall any safety briefing by cc stating that you must follow their instructions and no door to be opened except on their instruction. On the safety card the cartoons tell you to look out of the window and check it is safe. No mention of engines running or doing as you are told, interpretation likely to be act on your own initiative. Have I been characteristically inattentive all these years?
Edit: and for that matterwhy not a quick reminder before landing (sorry cc but you could usually omit the lifejacket rigmarole at that stage....)