It's probably also cultural. From my experience, Chileans like processes and bureaucracy. If there is a rule, the rule is followed even if the interpretation is wrong. Just an observation that was substantiated by a few people who had lived there. I gave up a long time ago with trying to deal with the tax issue with sloppy issuing. I tried to make sure it's there on the tax line, and if not then I just ponied up the 25 bucks instead of raising my blood pressure 100 points since I would ultimately lose anyway.