Hidden within the specs of many products are the performance standards they are required to meet. It's easy enough to ignore these things until you see what happens when something goes awry—as in the crash of a work or delivery van.
In the video above, a European manufacturer of vehicle racking systems shows what happens when a van outfitted with homemade plywood shelving crashes into a wall at the French test standard of 50 km/hr (33 mph).
It's impossible to tell how well (or poorly) the storage units were constructed. I suspect they could have been attached to the vehicle in many more locations. Still, the shearing through of the end panels suggests plywood was perhaps not the best choice of material for this application.
To illustrate the performance of its metal racking system, the company posted this video of their storage units undergoing the same test. The use of extreme slow motion cameras makes it possible to visualize the incredible force generated by the rapid deceleration of a crash. Tool boxes slide forward in a wave-like motion and the shelving units bend without breaking.
The possibility of the load shifting during a crash or hard braking is why many work vans are equipped with aftermarket bulkheads designed to separate passengers from cargo.
As you can see in the video above, you don't have to be driving at highway speed for the results of flying cargo to be dire.