The sticker is telling you that for whatever reason or reasons or safety factors or phase of the moon; the TT manufacturer is telling you the TT is designed for a specific maximum load.
My F-150's weight and max cargo is less than the axel ratings because that is what Ford wants based on whatever factors they consider.
You can play whatever guessing games you want, but you cannot change the fact that the TT maker only want you to haul a certain amount of weight.
You can ignore the factory numbers and haul what you like. I am sure many people do. But you do so at your own risk. At least when something goes wrong, you will know who to blame.