Is checking flight controls for 'full and free movement' not a legal pilot pre-flight responsibility? Buried somewhere in the CAR or CAO or Act of every jurisdiction I ever flew in, this one is up there with ensuring instruments work etc.
Are trims not 'flight controls' , albeit classified as secondary on some types?
In any case every checklist ever written says to check them. Where the FCOM is not specific, 'check' may be open to interpretation, but the word check implies more than a cursory glance. Depends on how one was trained in these matters, I suppose.
Of course it is impractical to check every single item, so much of our trust is with the maintenance people. But flight controls are in the 'easily checked' category, so why wouldn't you?. A whole lot more useful than flicking on landing lights to 'check' them, only to bring them one cycle closer to failure. Yet some pilots are absolutely diligent about this exercise in irrelevance, but can't take a minute to run the trims once a day?
But we are digressing from what we believe could have caused this crash. I certainly subscribe to the mis-set rudder trim theory. Whether or not it was properly checked pre-flight can never be known. Because of its mechanical design the trim wheel is highly unlikely to have moved full scale during the crash, so someone put it there. But all this has already been said.