Misalignment WILL cause steering vibration, but not everytime, only for few kms immediately after the alignment (especially the Toe) is disturbed (till the tire gets used to the new alignment). Take for example, when the car run over a considerable big pot hole @ laden condition and the alignment gets disturbed due to bent lower arms / tie rods. On driving, the tires will be stressed to follow a different path which they were not used to. At lower speeds this will not be noticeable. When the speed goes up, one could feel the mild vibration in steering for few kms. During this course of time, tire gets wear out to match the disturbed alignment. All these were exaggerated phenomena and could not be observed visually. Special equipment and detailed study is required to visualize it.