Taking a step back... I find it's helpful to remember that every time someone seems to be doing or saying something unconscionably stupid, or thoughtless, or evil, or otherwise behaving in ways that I want to classify as other-than-me, that's an opportunity to instead practice empathy and compassion.

I think this is an excellent point. From most people's own point of view, they never do anything stupid, thoughtless, or evil. Everything is justified as the best or only course of action that anyone they consider reasonable could take when put into the same circumstances. If you look at what they're doing and judge it to be stupid, thoughtless, or evil, and you don't understand how they could see it otherwise, then your model of them is incomplete. This method has almost always worked for me in terms of figuring out the missing bit of my model, and usually works for reducing frustration. (Sometimes my own emotional response is still "I know I'd do exactly the same thing in your place, but it's still freaking annoying!")