The key word being "qualitatively." Yes, something like a dependency can develop, but unless it's of roughly equal severity to hard drug dependencies, then the comparison is inappropriate. Hard drugs substantially affect one's agency, to a degree which sugar just doesn't.
Sugar is addictive, so talking about "individual decision-making" of millions of people like you did, like they lack willpower, is not going to improve the situation regarding the obesity epidemic.
You should do a bit of research of what can be found in supermarkets in developed countries of the EU, and what sort of food norms they have.
Of course you can put any problem on the fault of free will if you really want.
I think, generally, it is due to a lack of will, yes. Of course, eliminating the bad options altogether -- I mean, restricting what products can appear in stores -- would be more effective than relying on the willpower of individuals. Although, that would require some serious market intervention...