it all seems like the same process to me: being more interested in the difference between two values than in the absolute magnitude of them

You can go even more general than that - this really illustrates the entire, flawed process of the way that we think. Judgment and decision making seems to take the form of "use my subconscious pattern-recognition machinery to determine what sort of situation I'm in, then make a judgment of that situation based on just a few context cues." Manipulate the cues I rely on for judgment (such as relative magnitude), and you can manipulate the decisions I make.