NoCleverName, you are SO RIGHT! Fear only stems from a past experience - or wild imagination, which adults usually have much less of than do kids. So if after trying a couple of turns I feel uncomfortable and out of control, I will think that I am always out of control.
Poorly fitted boots, skis that are too long or too stiff or too soft or too short, skis with detuned edges or just with a bevel that I am not accustomed to, even poles that are too long or too short - all of this contributes to fear by making me uncomfortable and makes fear a self-fulfilling prophecy.
I think it's a good idea to have instructors have the equipment recommended for the level of skiing they teach. This way the instructor will be able to show the technique while feeling the same things the student feels. I remember all too well seven years ago taking Level 7 classes from an instructor skiing on racing-stock parabolic short skis (I think they were Rossis, but I may have forgotten) and in Lange boots while most of the people in our class were using the rental long straight skis and rear-entry boots. Needless to say, he couldn't show us how to be in control. To his credit, he could explain the mechanics of that, but there was no way we could see him do the very things he was explaining.