The moon moves, but very slowly, and for day/night cycles, you can think of it as essentially static (30x slower than earth moving 12 deg per night). Two points, therefore, 180 deg apart and within the plane of rotation of the moon on a sphere, cannot see the same thing at the same time. If the two points are not in the same rotation plane of the moon (for instance one at the North Pole, one at the south), then they can see the same moon. You would need to compare equatorial countries, or at least ones within +/- 25deg latitude of the equator to really prove the point. Can't compare a far north northern hemisphere location, and a far south Southern Hemisphere location because of the earth's 66.6 deg tilt from horizontal...;)