Hi there. I do not specifically know why, legally, they are not both considered disabilities. I would suggest though that both products are legal – and when consumed in moderation, they both do damage but … remain legal in their use.
Though it is legal to be an alcoholic, it IS an abuse of alcohol and has many severe health and societal side effects. Nicotine has health issues, obviously, but I don’t know that it has as wide an affect as alcoholism does.
Any addition is a problem. And when nicotine addiction creates the level of trouble that alcoholism has, they should both be considered a disability, in our books.
Thanks for the great question – you made us think.