My language was incorrect and appreciate you calling that out, I meant tow capacity may be greater, all things considered.
Title 49 U.S.C. and it's companion CFR certainly spell out the requirements for safe motor vehicle operation. The ratings assigned to pickups, cars, vans and other vehicles are governed by law. Interstate highways are controlled by Federal, State, and local laws. Intrastate roads have laws and regulations of the governing bodies overseeing the safe and proper use of the roads. Ignorance of the laws that govern such inter and intrastate transit is no excuse for common sense to be thrown out. These laws are there to protect us and ensure the freedom of all to use the same resource is not compromised by those who fail to follow advice and guidance from experts who understand the laws and regs along with the physics of safe travel. These laws require lights, seatbelts, restrict interstate use from horseback riders and pedestrians, and certainly governs proper weight for vehicles. Nothing against horseback riding and walking, enjoy them both - just using as examples of how wide reaching the guidance is.