I've had the vague impression that Italians are more touch-affectionate than "average" Americans (although I've seen major PDAs, even in the pouring rain), although in the northern regions this tends to be less the case than it is along the coast or futher sound. Expressing emotional intimacy, even in a platonic sense, through physical contact has always been something that puzzles me intellectually.

My impression was that platonic friendships among people of different genders in the US are often characterized by a moderate amount of touch affection, but I do see what you mean about how holding hands (and ironically enough, not making out) tends to be reserved for only same gender female friendships or romantic relationships. Only within relatively recent years have I reached the point where I felt comfortable enough hugging a number of my female friends, but I tend to be overly touch averse when it comes to even people I'm interested in.