Many invest in a country usually not because of the people who excel in mathematics. but they choose where it is strategic and the production costs are low. for mathematical intelligence it is related to how the individual's career will be, not with the country
In your words, they will be recruiting in densely populated, low-skilled and low-cost places to create their products. We need to take a scientific and valid look at the problem.
Mathematics is indeed quite important, but if you ask about factories, it will relate to human resources, where there are many workers that can be accommodated, investors will always build factories there. ofcourse mathematics also plays a role here, but in relatively small portions
Mathematics is useful for companies because it has a role in helping to create engineers involved in programming. These individuals will become human resources for businesses, whether large or small. Math skills also serve well in the work that requires logical processes. Employers will also look at the overall level of a country's education through the awards they win to calculate factory investments. The meaning of their team here represents a country, it is the average of the quality of the human resources, not just to a specific individual.