My source for this is the page you linked: "Humanitarian use" means "Use in developing countries (low-income, food-deficit countries as defined by FAO)". The FAO's definition of a low-income, food deficit country is that they're forced to import food because they don't grow enough calories to feed their population, and their income must also be below a threshold. See http://www.fao.org/countryprofiles/lifdc/en/
Though my information is slightly outdated in one area: the Phillipines are no longer on the FAO list as of this year because they're too wealthy.
"Really? 250,000–500,000 children in developing countries become blind each year owing to VAD, with the highest prevalence in Southeast Asia and Africa. I guess in your world that qualifies as effective"
Golden rice cannot help them under the current licensing regime, because most or all of those countries can't grow rice and even if the humanitarian use license did include any that could, it forbids exporting golden rice - it's strictly for internal consumption only. The page you linked makes this restriction very clear.