Well all strung necks have tension on them, the question is, how much compensation is designed into the neck such that it's "flat" (with the proper relief) on the plane of the strings when under that tension. That's where it gets tricky, especially with different strings having different tensions, and also, yes, Zon materials, design, and manufacture have tolerances. The truss rod, in the grand scheme of things, is nothing more than a secondary fine tune adjustment (unless the neck is crap, in which case you have a bigger problem and are trying to solve it the wrong way).
This translates to one Zon not being exactly like another at the very end (trust me on this, I own four of them, and have had three others fairly recently). I'm pretty sure that adjusting the trussrod to preference would be a "one time" deal as I'm confident that, once "set", like you said, it'll never move again from there... that's just a consistency thing. Wood would be the same way if it was hermetically seald from the environment, thus locking it permanently to a specific behavior from the date of final construction to forever.
In other words, regarding your statement on the effects of having a trussrod, "I reject your reality and insert my own."
