Boatycall, I can't say I really have any interest, and see no point, in going any further on this subject. As most of us know, the laws are not the same in every state. That suggest to me, we would have to argue this point one state at a time.
For whatever it is worth, at one time in California the license fees for pickup trucks was based on weight, if the vehicle weighed over 5000 pounds(as I recall). Years ago, I got busted for having a flatbed registered as a pickup, and had to have the truck weighed. When I brought my current truck into Calif (about 2001), I had to have it weighed for licensing. I do not know the current laws. I do know, I had the typical commercial license, then got the Handicap license. My fees were $298 per year, and dropped to $93 per year and it is still a commercial truck. I see no place where weight entered into it.
Wayne