Trucker's have a lot of rule's to follow, They have to keep track of their hour's behind the wheel, their cargo, their weight ( the truck....not themselves) ect. ect.
They must stop at Port of Entry / weigh station's for weigh -in, and the "occasional" inspection.
Most state's have a 26,000 lbs cut-off for commercial vehicle's. Under 26,000 lbs your not required to stop at weigh station's ( This varies by state )
but quite a few state's require ANY commercial vehicle to stop ( this include's anybody with a business logo on the side of their vehicle to stop.... even if it's a small pick up truck.
The "Not For Hire" logo tel's law enforcement that " This is NOT a Commercial vehicle", and therefore not subject to carrying logbook's or weigh -in's . HOWEVER: there are a few state's where this is changing ( Arizona has become quite "Draconian" in it's stupid catch-all law's . to the point that if you rent even a small U-Haul to move from point A - to - B you have to stop at weigh station's . No matter what you weigh ! Even if you are a "Private citizen ! And if you packed it wrong and have too much weight in the truck, your gonna get a ticket !)