Why Italian Americans instead of just normal Italian? Aren’t Italian Americans just regular Italians? Or are you asking about the customs of Americanized Italian families or people who were born and raised in America but with Italian ancestry?
Probably because they don't know any Italians (in Italy), just Italian Americans.
Italian-american cuisine is quite distinct from Italian cuisine (which is really a lot of regional cuisines with a shared language and some shared staples)
Are you a non-American?
It is typically the custom of Americans to hyphenate our ethnicity and claim descent from some European country or another. (Or African or Asian, or wherever the family had migrated from.)
Indeed, an Italian-American is not a "regular Italian" because they enjoy neither citizenship nor residence in that sovereign territory. Italian-American cuisine is also unique, and distinct from "regular Italian" cuisine. Sure, they draw a lot of ideas from the Old Country, but c'mon: tomatoes originated in the Americas!
I could be known as an "Irish-American" but really, I was adopted by a non-Irish family, and the Irish clergy/religious who educated me were fully inculturated into the United States, so we learned a patriotism for our homeland, along with a very American faith and culture, and not a futile nostalgia for some long-lost European territory. There was not a trace of Celtic spirituality or "Irish Republican rebellion" taught to me or my classmates.
I do appreciate Irish culture from afar, and I enjoy the St. Patrick's Day festivities that are not drunken orgies, but I am constantly reminded that I was never "Irish" and I do not derive my identity from hyphenating such things.
Because those are the Italians I have experience with, and the Italian Sugo al pomodoro isn't to my knowledge ever cooked for hours. The slow cooked variety in Italy is the ragù which is cooked up to 4 hours. If you cook any tomato sauce much beyond 4 hours you lose the actual tomato flavor[1]. So I sincerely doubt forever tomato sauce is a real thing.
[1] https://www.seriouseats.com/the-best-slow-cooked-italian-ame...
> Aren’t Italian Americans just regular Italians
No. The term generally refers to a groups of people descended from Italian immigrants who formed their own culture in America that blended regional Italian languages and cuisines with local American ingredients, language and customs. The big pot of red sauce in question doesn't exist in Italy, it's an invention of early 20th century Italian immigrants to the US.