Bullshit. Yeah, calorie counts on packaging is imprecise. Yes it's difficult to know for sure. Yes there are a lot of small factors that go into it.
You know what you do with fuzzy measurements and personal bias? You over-count calories and round up deliberately to off-set it. You know what you say when someone tells you that your micronutrient balance isn't just right? "Probably. But obesity will kill me before that will."
Source: one drunk guy who has lost >100 pounds and kept it off for 3 years.