I'd be totally okay for them to charge by total weight/mass (passenger + luggage, etc.) Women would come on top (on average) call it even with regard to haircu

I'd be totally okay for them to charge by total weight/mass (passenger + luggage, etc.) Women would come on top (on average) call it even with regard to haircuts --children also get cheaper seats and it's the fairest system even if they have to set a "floor". The more weight or mass the more fuel is consumed.