Given how difficult it is to tell the age of some teenagers, ans the amount of time security staff spend scrutinising the photos on ID cards, how are the Police supposed to look into the dark interior of a moving car, instantly assess the ages of any non driving occupants, and pull the car over, by which time any cigarette would have vanished out of the window, and the smell is because I sometimes smoke in the car when the children are not here, officer ... repeat for every car the Police see, every day, because it will be the "in fashion" rule of the moment.
The Police must really be looking forward to having to enforce this one.