Why does the slider conflate position with velocity? Leave it at 0.95c for a minute, put it back to zero, then watch as your position is re-set back to 0. Sub

Why does the slider conflate position with velocity? Leave it at 0.95c for a minute, put it back to zero, then watch as your position is re-set back to 0. Subsequently slide it back to 0.95c, your position is magically fast-forwarded to your previous position, along with resumption of velocity.