What suprised me most is that cabin crew sometimes are apparantly afraid to do something about passengers who not obey the fasten your seatbelt sign. On my recent Sao Paulo - Paris flight a passenger opened the overhead locker (and left it opened) while the plane was taxiing at CDG airport. None of the cabin crew bothered to close the overhead locker and talk to that passenger even though one cabin crew member past the overhead locker.
Allthough it may be good there is a law against not wearing your seatbelt when the sign is illuminated you also have to have the cabin crew to enforce these laws. Unfortunately I don't see this happen.