We do have the ability to use commom sense.We use it all the time at work. Well, most of us do, and pax do too, well most of them..
Slamming on the brakes means, slamming on the brakes, they can stop pretty quickly if they have to.Before takeoff, it's just the crew that go A over T. They were all a little shaken, had been lifted off the ground, would you believe! Bumps and bruises, no head injuries luckily. It was decided that they would carry on.
elsewhere there was a question re crew out of their seats b4 takeoff, the answer was something to do with balancing the product, with safety.
Of course I was exaggerating re 30 or so, but if you let 1 up, who knows how many will follow...