I think those are mostly surface similarities, and are tropes shared pretty broadly in sci-fi. Moreover, I think that if you dig a little deeper into the AT-43 backstory (which, to be clear, I do not play) you discover that [SPOILER ALERT! HIGHLIGHT TO READ] the Therians are actually humans from Earth who've modified themselves into a cyberetic existence.. As for the U.N.A. and Red Block...well, that would mean that any United Nations variant is a ripoff of the U.N.E., and anything that resembles the Soviets is actually a Fantasian clone. That seems like a stretch.