Skut,
As far as I am aware, the responsibility of the standard weight is determined by the individual carrier usually the ops standard dept. Unlike a freighter the weight and balance for passenger aircraft is really the closest estimate weight you can get. In regard to standard baggage weight usually only apply when the load controller is doing their weight planning. When they close up the flight the weight used usually is dividing the total weight by number of pieces to give them an average baggage weight for the calculation. Should there be any overweight baggage it usually reported to the Load Controller in advance before the load plan complete. Most people just interest in getting it in trim, within the limit and let it go. I used to do some weight and balance for our company aircraft when on diversion, or like Paris the strike of the handling agent means extra work for us in the ops room.
There may be other way to work out the weight, I am not an expert on this topic but hope the above info would be of any help.
