@dagosa, before in this thread, I said that I was not about to criticize you for erring, however severely, on the side of safety. That is your choice, and your life.
However, when you go beyond your own personal choice, and start to cajole and guilt-trip others based on their choices…at that point, I feel criticism is fair game. And as a fair criticism, I think it is absurd to argue that an appropriate standard for securing a load is “turn the truck upside down, shake it…and see if anything comes out!” Few cargo vehicles would pass that test: a car carrier would shed cars, a brick carrier shed bricks, a “van” trailer would have its thin metal skin shredded, and a landscaping pickup would be tossing zero-turn mowers about the highway.
About the only truck NOT expected to shed load is one carrying something like the 16,000# steel coils they ship out of the mill, and think about how they’re secured: multiple chains around each, wedged in place, and wrapped around the trailer frame! It also takes several hours to secure such a load–a reasonable burden to the “civilian” just trying to get up his driveway?!? NOT!
As far as the law, a reasonable standard for “secured” load is one that stays put during foreseeable NORMAL operations: if it stays put in a multi-vehicle pileup, a pleasant surprise. Think: to ensure security in a rollover, you’d need, at the least, multiple chains, or wire rope, around each and every object in the bed…and secured on the other end to the actual vehicle frame, not wimpy sheet metal that WILL deform and tear when wrecked!
(I also don’t see how sand bags are any improvement: if 60# of sand in a tough canvas bag is flying at your head, 60 MPH-ish, you’re every bit as decapitated as if it were concrete block. MAYBE it’d do better against a “hardened target” such as a car-like metal box…but I’d want to see the “ballistics” on that one before granting anything!)