Are you serious?
Look at the frame, axles, and the 19.5" wheels and tires that truck has. That is why it has a higher load capacity, not because it has more axles or whatever you may think.
A pickup on 16" tires and wheels cannot be compared to something like you've got pictured above with HUGE axles and wheel bearings, springs or air ride, an 8" tall heat treated frame, etc, and you'd be a fool to even think of comparing such a truck to a pickup.
There is no question that a pickup is capable of pulling FAR heavier loads than it is rated for, but that doesn't mean it is safe, or right.
Manufacturers test to see that their vehicle can safely tow their rated load under even the worst operating conditions. That is why the limit on paper is much lower than the point at which it will no longer pull anything else. There has to be a safety factor in there....but I see no point in pushing it to the limit either way.
Yeah, I know nothing about towing at all....that's why I always check my rig, I have the proper hitch, tires, trailer with brakes, tiedowns, etc. Maybe I'm paranoid, but I just look at it as doing the job the right way.
As to the above vehicles being DOT legal, great, but I'd love to be the lawyer on the plaintiff's side when you get involved in an accident and although you're plated for 30k lbs your vehicle's GCWR is 17000-20000. I'd love to see a judge make a field day out of someone that would overload a truck by 30-40% and insist that it is safe because it has a certain license plate or the driver has a Class A license. You'd be a fool to think that makes such action safe in my opinion.
You guys might think I go overboard, but I wish more people on the road would pay attention to ratings. One day, it will all come back to bite us when the lawmakers realize what people are doing. If nothing else it'll be another potential for income for the government, and they'll write people HUGE tickets just because they can.
IMO, a truck should not be overloaded under any circumstances, and any arguement to the contrary is foolish.