So, the chains broke when doing an emergency braking and the load crushed the pick-up? I clearly see that the driver was at fault, but aren't loads also not supposed to easily escape their tie-downs?

Some loads like this one are so heavy that you just can't defeat their inertia, hence why you go slowly and have a large escort. It couldn't be stopped that quickly just due to the nature of the load.

At some point if you're getting behind the wheel of a vehicle on the road, you have some responsibility yourself. If you're not looking where you're going at all and drive into the path of a heavily-escorted million-plus-pound load and it ends up crushing you because of the sheer physics of the situation, that's on you. There's a hundred other more likely ways to kill yourself on the road if you're not looking where you're going, that don't involve such unusual cargo.

And also, from looking at the photos of the scene, it looks like the driver may have turned quickly to attempt to avoid the crash, and the load continued on of its own inertia and overturned the entire rig, which is an issue caused by top-heavy torque that doesn't care how tightly the load is tied down at all.