Just a wild guess but I'm thinking if a vehicle is so over loaded that it's unsafe to drive, it's "unsafe" characteristics will be evident in the driver's inability to maintain control of his vehicle such as being able to stay in his lane or stop in a reasonable distance or even accelerate up to speed so as not to impede the normal flow of traffic. In that case I would assume a police officer would notice the unsafe condition and possibly ticket the driver for careless driving, reckless driving, failure to maintain control of his vehicle, failure to stop at a stop signal, maybe even improper equipment as a result of being severly over loaded to the point of impaired driving. Hopefully none of us will over load our vehicles to the point of being "obviously" grossly over loaded. If simply being over the manufacturer's GVWR were illegal, police depts could fill their coffers with fines collected from just about anyone loaded for vacation in their cars, minivans and SUV's. Even the minivan loaded with kids for the soccer game would likely exceed the GVWR. Heck, they could sit out in front of Home Depot and rake in more fines than DUI check points outside the bars.
