I think sugar consumption is not unique to Lower-income countries. A study showed that a US kids consumes more than 49 pounds of sugar a year. All these are the processed food from the big box grocery stores. I suspect the sugar consumption is way less over in those countries where as a large segment of the population is unable to purchase processed food from the expensive grocery stores. Also sugary drinks are consumed by the kids at school to get some energy, many are unable to afford a breakfast and opt for that sugary syrup sold at the school canteen.