I completely agree.
Related to that, can we safely assume that "fairness" is like beauty -- in the eye of the beholder? For example, North Korea may think our relationship with Canada is unfair to North Korea while Canada might think the USA is unfair because of what they believe is our exploitative harvesting of fisheries near Canadian waters. Etc.
Meanwhile, back at the ranch, our concept of fairness among elected officials and citizens varies considerably. I might think that the Kyoto Treaty is the answer to a looming global catastrophe while Germanstar might think it's all BS and we should burn goal for home heating (just kidding, GS).
Also, our concept of fairness has a relationship to time. In which long-standing good (or bad) relations affect our view of fairness.
Does anybody suppose that there is an objective fairness -- a fairness that exists outside of our perceptions and beliefs?
Inevitably, one country or another may get their nose out of joint based solely on the "me-too" mentality of whomever might be in charge at the time. The role of diplomacy is to smooth over these bumps, and let everyone know that "fairness" sometimes ebbs and flows, but that we try to minimize wild swings in handing out, taking, or accepting favors.
In fact, I've no idea why we have to declare a "most favored nation" from the standpoint of trade. That can't send a good message to the rest of the countries with whom we deal.
Contrary to what some might say, I don't think that these types of engagements are anathema to the good Dr. Paul. He's not an "isolationist". He believes that we should have open trade and relationships with all countries, but close political or military entanglements with none. It's a small planet, politically speaking. The rule "don't shit in your own back yard" should apply to our dealings with everyone.
Ultimately, the axiom "perception is reality" holds true. If someone perceives that they're being slighted, then that is their reality. It may not be fact, but I take the position that one cannot be blamed for their honest perceptions. Rather, it is the job of a diplomat and/or a leader, to ensure that such problems of perception are taken seriously, and rectified - equitably.