You're dead on right. There's no excuse for those travesties. The primary difference is that our voters wouldn't accept those kinds of abuses in our own country. Yes, too many voters are willing to turn a blind eye to exporting those policies, but at least those who are aware of them are both able to agitate against them and, occasionally, able to stop them. There is no fundamental difference between Guantanamo and Russian or Chinese camps set up to torture Muslims. We do, however, still have the right to investigate and to protest; I believe this has limited the scale to one concentration camp as opposed to dozens or hundreds. The same applies to our foreign policy. And there are times where it makes sense to back the less-immediately-dangerous of two dictators, or even the one not aligned with our adversaries. Even in those cases, there's been an almost ridiculously naive American will to try to get them to accept free and fair elections, such as in Iraq. I don't think there's any other empire in history that would allow, let alone sanction such a thing, with the exception of the British who were also primarily interested in divesting themselves from their imperial holdings.
On the foreign stage, America does and has backed horrendous dictators and fascists. As does and has every other empire in history. There is, though, a certain underlying theory in American politics - both right and left - that is disgusted with the notion of engagement in foreign wars and doesn't have the will to occupy foreign territory. This is what you would hope for as a natural result of a functioning democracy where people had a short tolerance for the personal deprivations inflicted by a state bent on imperial expansion.
No, it ain't Switzerland. I wish it were. But speaking with Syrian refugees and Lebanese and Tibetan dissidents and South Vietnamese and Cubans I've known in my life, I've kind of come to the conclusion that international relations are a jungle where most states are predators and most individuals are prey. America does at least give lip service to the notion that individuals shouldn't be preyed upon, and tries to export that meme.