I suspect it varies by country for a multitude of reasons. The first being that each country is run by a different government. Each government is run by different people who probably made up these recommendations based on the information they were given. And the information probably varied a bit, along with their own biases, cultural expectations and how much they knew about nutrition. I'm certain those things would lead to some variability.
Second, it probably has to do somewhat with location and culture. In places where it is typically sunny, you may see less of a need for vitamin D than in cloudier places. In places where fresh fruit is readily available and is part of a normal diet, you may see less emphasis on supplemental vitamin C (or other things). The recommendations will probably emphasize fixing deficiencies in a culturally normal diet to make sure babies are getting what they need.
Third, as pointed out by @Stephie in the comments, there isn't a one-size-fits-all list of nutritional needs. Even in the U.S. (where I live), any food nutrition labels are based off a certain size diet and a nutritional guideline. As with all guidelines, individual needs will vary. So some countries might recommend more of something in an attempt to cover their bases (assuming more of something wouldn't be harmful). Other countries might be less inclined to recommend excess nutrients in favor of a more baseline approach.
Fourth, typical genetics of a country. Say you were talking about a country where anemia was somewhat common. That country might just recommend more iron to try and prevent problems. In a country where there is less of a predisposition towards anemia, they may not make such a recommendation.
There are many reasons why the recommendation might vary. But the short answer is, every country, culture and person is different. We all have different needs. So different recommendations are required to cover a typical case in a certain country or region. There is no one answer for everyone, so there isn't one recommendation that works for everyone.