That song is all about how the war was bad because it was working class people fighting and dying there, and not the sons of the rich and powerful. That's a great summation of the "pop" anti-war movement at the time: the war is bad because we're getting drafted. Very little or nothing about "oh hey this war is bad because we are committing tons of war crimes and atrocities at damn near the same level as the SS". Or even "hey maybe we have no business at all stopping a communist movement in another country when that's what their people want". Nope, all about US and how the war impact AMERICANS. And then when the war ended it was retroactively considered "bad" because we lost and because it made the veterans sad. God boomers suck.
Of course at the time there we plenty of folks who were anti-war based on solid principles. But what do you know, they happened to be leftists like the Black Panthers. Just another example of the left holding the torch for what is right while the rest of the country acts like fucking depraved assholes.
Edit: listening to the latest Chapo episode now, Matt just reminded me, once the draft went away the anti-war movement dried up.
The song itself I think is correct in pointing out the class issues with the war (and really, most wars). My issue is that it seems like, whether we're talking in 2020 or the 1960s, the actual suffering of the Vietnamese people is at best, a tertiary concern regarding the war. I don't doubt that many/most people figured the war wasn't worth fighting for. But I don't think that's at all the same as saying this war is bad because we're genociding a country. It keeps the focus on America when really I think the focus should be on Vietnam and what they had to endure.