please reread my post, I added some stuff in the time you were writing. Restraints are designed for certain heights, which those restraints can only go on certain vehicles, and they have to be safe. It's not as simple as that, but that is the bulk of it.
Restraints aren't designed specifically and exclusively for certain heights. Every type of restraint used to today could be scaled to the height of the expected rider* The type of restraint used also evokes mental states, see Alien Encounter.
*rider that is old enough to support their own body weight and developmentally mature enough so as not to require a bio unit to accompany them (was this disclaimer really necessary? probably the way things go around here)