Those things look ridiculously well-made. Moreover, the thread is not simply cut in the nut, but rather a threaded insert is joined with the nut casing. That looks like it is more expensive to make, and could be an Achilles' heel if it is botched in production. Suppose a manufacturer cuts costs by using a cheaper metal for the casing, thinking only the threads have to be good quality; but then the nut is easy to strip. What if the two parts expand at different rates under heating.

By the way, you can use two nuts to prevent loosening:

http://en.wikipedia.org/wiki/Nut_%28hardware%29#Use_of_two_n...

this could be cheaper than a much more expensive single nut. This article section explains how vibration causes loosening. The second nut ensures that the first nut stays in firm contact with the bolt threads even during moments when the pre-load is momentarily lost due to vibration, and so cannot rotate loose.