I'm not sure. Part of it is likely cultural, since Italians tend to live in multi-generational households with old-folks and young people in close proximity. They are also a close-talking, affectionate people. Italians kiss hello, kiss goodbye, etc. They are also a population that smokes a lot of cigarettes.
Right now, Texas and Florida are having terrible issues. But my guess is that is more just reckless disregard for precautions than anything else. There is plenty of space in those states to socially distance yourself in most scenarios.
Edit: I also just remembered that Italy has a much older population that many other countries. The average age of an Italian is 7 years older than an America. That's very significant, considering the people most affected by Covid.