We purposely put them in the "tall" position, as that's their designed settling/standing point. Then applied the straps to pull them down toward the bed. This compressed them into a solid position. It was a short ride and I drove like grandpa. Mission accomplished. Took two guys to load, and just me to tilt down and unload. Always wear gloves.
We cheated, a little. When these shelves were first assembled, we added a spot of adhesive to the joints, with the idea that we were never taking them apart. They are one solid chunk of shelf. But generally, I would agree with you, these things want to disassemble themselves.