The are vast differences in the way each state classifies their vehicles for registration purposes. What's legal in one state may be completely illegal in another.
Most would agree the manufacturer, who engineered, designed, and tested, any given vehicle, is in the best position to know the suitability of their product to carry a given payload. There are legal implications for the manufacturer if their product is proven unsafe when carrying recommended loads. It's in their best interest to be accurate. In any case, the Maximum Payload Sticker is one of several evidentiary tools that may be used in any legal process that involves an overloaded vehicle.
