Comparing average IQ scores doesn't work the same as comparing individual IQ scores. That's because the scores are normalized to produce the number.
When you compare country averages, the mean world score must always be 100 as per definition of the scoring system. Likewise, the standard deviation must be 15 points. Since the average scores in each country vary less than the scores of individuals, this has the effect of forcing the average IQ comparison into showing large differences where there aren't any.
For example, in a hypothetical IQ test, the individual participants may receive a score from 0 - 200. The variation seen in testing shows most people getting raw scores between 50 - 150. When you divide these people into groups, and measure the group average scores, you'll find that the average raw scores have a much narrower spread. Maybe 90 - 110. That's simply because in statistics, a sample mean tends to approach the population mean with larger samples, and deviate more with smaller samples. The average of two people varies much more than the average of 200 people, or the average of 2 million people, etc. Even if there were some genuinely stupid people in the group, the whole group average would still tend to be closer to the world average the larger the group is.
How the IQ score system works, take this spread of raw scores, and whatever standard deviation it has, that's 15 points. Thereby, getting a score of 65 in comparison between international averages doesn't actually mean the average person of a country would score 65 points when measured as an individual, because the deviation that the score measures is not the same. It would be like measuring in inches vs. centimeters and pretending that the numbers mean the same thing.