Part of it is the initial conditions of states experiencing socialist revolutions, as those generally don’t happen when things are going well, and fighting during the revolution itself will also destroy some infrastructure, so even the more powerful of those states start on the back foot. In addition, during World War 2 both China and the USSR saw major invasions by the axis power causing even more damage to them, while the mainland of the US did not see any fighting which allowed them to maintain their productive capacity and infrastructure. Due to these factors, the western powers did have more resources to inflict and resist sabotage. That is not to say that it was necessarily the only reason, but it was certainly a significant factor.

No Man’s Sky is not as focused on realism as Elite : Dangerous, the planets are at fixed points within the system. The resources used to fuel your ship in NMS are found on asteroids and planets.

In earlier versions the sun was a part of the skybox rather an object within the gameworld, so it couldn’t actually be visited, which you can now do with this new update. Haven’t tried it myself, but from what i have heard it takes somewhere between 5 and 15 minutes to get there (probably depending on how upgraded the impulse drive, this games equivalent of supercruise, is) from the systems hyperspace exit. Should drop you out of impulse at a certain distance, planets and other points of interest do that too. Getting too close deals constant damage to your ship.