see previous ....
when people actually listen to the safety brief they will know not to try and get the trolley bags before evacuation.
Cabin crew will also go down the cabin to ensure that tables are stowed, seats are upright, belts are fastened, earplugs to iphones etc. are out, and blinds are open.
What people do after that is basically down to whether they respect the cabin crew and the advice they were given.
There are plenty of travellers who think they know better, and the cc cannot be expected to police them all, all of the time.