i don't know. i do believe it is true (chileans i know that have lived in argentina are mortified by the corruption there), and the country is very isolated culturally (by the andes in the east and desert - and poor relations politically - to the north). so it's reasonable for it to be different, but i don't have a good explanation for why it is.
whatever the reason, it seems to be quite deep, culturally. anecdotally, i was shocked just a couple of weeks ago when i went to get a picture framed and the people doing the work lied to my face (they said between themselves that they didn't have the material i wanted; when i questioned that they promised they did; the results were not what they promised). that was very odd for chile (sorry, i didn't make it clear above - i live there), but the shop owners were argentinian immigrants... it is normal, culturally, here (speaking in broad terms) to speak "optimistically" of the future (so if you ask whether a shop will have something in stock next month, they will - usually, in my experience - say yes), but not to directly contradict what was said a moment earlier without batting an eyelid (i should perhaps add that i suspect i missed something myself in the exchange in the picture shop - perhaps the expected way i should have behaved was to offer an acceptable compromise instead of directly questioning what was happening - i am aware that cultural distinctions are not absolute judgements).
