Guilty as charged. That is one of my flaws: I tend, where possible, to try to check my facts rather than relying on half-guesses and assumptions before I say something.
As it happened, I had researched this for an upcoming trip so was very aware of the gap between resident and non-resident fares.
Indeed and why should you? But it also explains why you write what you write. This is something that does not really affect you. Those of us who, as visitors, are affected by this and therefore have a stake in this matter are very aware of the substantial differences that exist between resident and non-resident fares.

Ignoring the fact that the majority of readers of this forum who are just visitors to Argentina than residents are far more likely to be members of a North American and/or European FFP than one of Lanpass, even with Lanpass it would mean that I would earn approx US$10 worth of miles for paying US$187 extra in fare. Don't know about you but I can't say that I am hugely impressed by those figures.

What do you mean by "factor the economic situation here"? Whatever the economic situation in Argentina, 25% less in my wallet is 25% less in my wallet. If what you mean is that it is justifiable for residents to have fares which are 25% lower than non-residents, then fair enough and, as I said in my earlier post, I can fully understand there being lower fares for residents. But a justifiable difference is not the same thing as a negligible difference and what you said was not that there was a substantial but justifiable difference but rather that the difference was small ("not that much cheaper").

25% is imo a big difference. Moreover my point was about the double-whammy: non-resident fare + inflated rate of exchange. When you add the rate of exchange effect (which adds another 50%), you end up with a typical differential of 75%.
I would have thought that, for the majority of flights, the risk is more one of being sent back to the ticketing desk to pay the differential with the non-res fare (since tickets are changeable and therefore should be upgradeable to a higher fare class/fare basis), viz. close to what you would have had to pay anyway had you paid a non-res fare in the first place, so the downside is not quite that huge. If you are traveling without luggage and OLCI, judging by reports here and there on the internet (not just the gringoinbuenosaires 2010 blog entry but also reports as recent as late 2013), the odds of not making seem low. Clearly, if you have hold luggage or are traveling on a busy day where flights are likely to be all full, it would definitely not be a smart move. In other situations, however, the risk matrix looks like: seemingly relatively low risk of being caught + not a huge downside if you are caught = reasonable risk. Now it may well be that LA has tightened up its procedures in the last year, making it a higher risk. I don't know but, given the limited downside, this would be something that would put me off just based on the risk equation.

No, for me, it is not so much the risk, which would be acceptable to me, but rather the feeling of not doing the right thing. OTOH, the double-whammy also does not feel to me like the right thing either. So there is something of an ethical dilemma which I am happy that LAN's cybermonday sales saved me from having to face.