When you refine the addictive, pleasure-causing white powder out of a plant and make cocaine or heroine we call it a drug. For historical reasons when we do it to make sugar we call it food, but it seems more of a drug.
Maybe drug regulations should apply.
Since most plant foods we eat, hell, even breast milk contains the exact same sugars that are refined into table sugar, syrups, etc. and the chemicals themselves are required by the body for things like brain function, it's probably fair enough to call it a food...
>"There are records of knowledge of sugar among the ancient Greeks and Romans, but only as an imported medicine, and not as a food. For example, the Greek physician Dioscorides in the 1st century (AD) wrote: "There is a kind of coalesced honey called sakcharon [i.e. sugar] found in reeds in India and Eudaimon Arabia [i.e. Yemen[17]] similar in consistency to salt and brittle enough to be broken between the teeth like salt. It is good dissolved in water for the intestines and stomach, and [can be] taken as a drink to help [relieve] a painful bladder and kidneys."[18] Pliny the Elder, a 1st-century (AD) Roman, also described sugar as medicinal: "Sugar is made in Arabia as well, but Indian sugar is better. It is a kind of honey found in cane, white as gum, and it crunches between the teeth. It comes in lumps the size of a hazelnut. Sugar is used only for medical purposes."[19]" https://en.wikipedia.org/wiki/History_of_sugar
And one of the mechanisms proposed for smoking addiction/withdrawal is that smoking spikes your blood sugar, while abstaining crashes it. Ie, a smoking habit may actually be an indirect sugar habit, although somewhat more addictive since you don't have the delayed reward due to digestion/absorption. Eg:
http://whyquit.com/joel/Joel_03_21_blood_sugar.html
https://www.ncbi.nlm.nih.gov/pubmed/7455580
EDIT:
I guess I should add I'm not in favor of any regulatory approach beyond the FDA's original purpose of making sure the label is complete and accurate.
Seems more likely that it's because people eat sugar, and they don't eat heroin or cocaine.