Why is this not mandatory for take off and landing? I cannot recall a flight attendant checking the shades before landing or takeoff. Yes, it does make sense that if the plane goes down, rescue workers would have a better opportunity to see the seats. But, I want to receive safety instructions from the crew, not the person sitting next to me.

Once the instructions have been given, and it's perceived that someone is violating safety procedure, it is the crew's responsibility to enforce the regulations.

I recall one incident when the regulations had been changed allowing cell phone use until the door closed. Prior to that there was no usage allowed at any time. A passenger was talking on the phone and another passenger kept yelling at him to turn it off. It became very heated and loud. It almost escalated to a security issue when finally the FA advised the non caller of the change in regulation.

His voice level was reduced by 95% as he sheepishly said "sorry, I guess that's new."