Understand that companies may wish to charge for excess baggage and thats understandable.
Just wondering how often the airport scales are checked by the appropriate weights and mesures authority.
If your charging based on that weight must be approved for trade and checked.
Think a guy got off a parking fine a while back by showing that the time clock in the parking meter hadn't been calibrated and could have been inaccurate. You also see stickers on fule pumps and supermarket scales showing when they were checked for accuracy. What a nice little earner a 10% error could be. Weigh your bags when you get home.