Possibly because you can completely avoid alcohol but you can't completely avoid food. Some large percentage of people who would have been addicted to other substances (due to less than optimal nature/nurture) but didn't, because they did not take those substances, instead became addicted to the substance of food.

It might be more useful to see addicts to every type of substance as a large pool of anxious people who came across a substance to self-soothe, and figure out how to address the anxiety problem first.

The US population probably isn't much different from the rest of the world, in that regard. What's different about them is they live in the US. Drop foreigners from skinnier countries in the US, and, as a cohort, they'll gain plenty of weight (as with lifelong Americans, some individuals will buck the trend, of course)

It's a complex social-environmental, economic, and political problem.

Cheaper, much easier to get, socially acceptable everywhere, ...

You won't get judged for eating alone at home, but start drinking alone at home...