fla-gypsy wrote:
Because no one could ever perfectly load any vehicle
That is the correct answer! The higher values for each axle allow for variation in front/rear loading without exceeding the overall max ratings provided by the vehicle Manufacturer. While exceeding GVWR is not illegal (except in BC,Canada), exceeding axle ratings usually is as they are often based on tire capacities.
Having said that, exceeding GVWR can open up a can of worms in regards to warranty issues and even liability in the even of an accident.