I believe that there is an allowable margin for error in the nutrition label and that below a certain threshold they do not need to report a nutrient value...so I expect that when only small amounts are involved they might tend to under-report. I'd like to think that these labels are completely impartial and based on assessment at an independent laboratory, but I suspect that the food industry could just as easily exploit any loopholes in the system and use them to fool us that their product is better than their rivals. Consider that "Lite" can mean anything from weighing less, to lighter in colour, "low-<whatever>" is usually only "low" in comparison to one of their own products that contains huge amounts of <whatever>, and my all time favourite "no added sugar"

They are in the business of making money after all.