For obvious performance reasons, jetways are initially created as a static model, and will activate only when selected. If we wanted to randomize their starting position, it would result in a very bad switch from the static (which is always the same model), to the dynamic version.
And, of course, making different variations of the same static model, in addition to result in making the number of installed simobjects to explode, slowing down the simulator startup, causing an fps loss caused by the simulator not being able to optimize instancing of the same model, with very little in return, other than some randomization in the initial position.