Originally Posted by zaphod424

This is an interesting point. Part of the reason airlines went with distance/sector based systems in the first place was to keep it abstracted from the money being spent, so as to make it basiclaly impossible for governments to tax, since there was no real link between points and currency. But if they're going to base rewards on spend now it allows governments to much more easily assign a real monetary value to these points, and therefore tax it.