One should not infer from "In a non-uniform gravitational 'field' . . ." (third link) that tidal forces are absent in a uniform field. Take, for example, a g-field uniform in the x-y plane; in this instance there is always curvature in the z-direction. That is to say, two observers in free-fall who are a finite distance apart along the z-axis will accelerate relative to one another even if both measure the same gravitational acceleration gz locally.