For Lucas, it’s just valent to his prequels (and the context of the 70s) that his Empire is America. It’s a reflection of Star Wars’ contemporaneous moment. One of the most ‘revolutionary’ times in pop art and music.
Oh sure, it’s clear from characters that say things like ‘I’m not in this for your revolution sister,’ that certain contemporary ideas are being pulled in. Or at least ones from the previous decade. I just feel like because of the prequels having to be part of his ‘original vision’ these elements like the ‘war on terror’ have to align with earlier social issues. So of course he will say it was always about Vietnam. It was always six movies, and so on. I just don’t really see the broad strokes in the OT at all. So I guess we can agree to disagree.