At the moment a weight is assigned to a male or female passenger, without weighing them, how many actually are this weight? I know I'm not, times that by 400+, and you will see that aircraft already operate like this anyway, so I don't see the problem.
The other day my hand luggage was weighed at 5KGs, after passing through security I added another 10Kgs in duty free sales, times this by 400+...............
