Why anything containing psychoactive drug is actually legal to sell to kids? There's a lot of reports how bad is caffeine to underdeveloped brain. And look at any developing nation: everyone is hooked to Coca-Cola.
Not going to do well on this site if you make baseless nonsensical claims like that.
Paper[1] from 2009 stating that: 1. We actually use caffeine as a first-line treatment in premature infants for treating apnea and 2. Nobody has done the research on adolescents to assess any negative impact on brain development.
Everyone (more or less) is outside a few liberal, urban, health-focused pockets of the US, too. Or to sweet tea, or some other sugary caffeine drink. Unless you intended "developing nation" to cover those parts of the US, as well :-)
[EDIT] Not sure what rubbed people the wrong way about this, but if it's the qualifiers then it's my understanding that both "liberal" and "urban" are, independently or together, correlated with smaller waistlines and healthier lifestyles, in the US. Almost certainly including consumption of sugary drinks (indeed, this seems to peak in the "deep red" South, in the US, from what I can find). If that's wrong I'd be interested to know about it.