I believe that Italian-themed restaurants in this country can be placed as under one of broadly three banners: Italian-American, Americanized Italian, and Italian.
Italian-American easily claims the largest number of restaurants and also dishes in the popular mind. These restaurants serves items that come largely from the Italian-American tradition like those spaghetti and meatballs. The preparations in the Italian-American tradition are rooted in the big wave of Italian immigration from the 1880s until 1924. The vast majority of these people came from the Italian south where the tomato has a prominent place, and about half the dishes in the Italian-American canon originate in the Naples area like long-simmered tomato sauce, pasta and clams, and lasagna made with tomato-sauce and ricotta. These dishes might have had roots in Italy, but were adapted and grew with American tastes, abundance, industrialization and pace of life. The people who were eating these dishes were Americans, as the immigrants’ offspring and descendants were plus the generations of restaurant patrons. The preparations at these restaurants, regardless of the provenance of the recipes, are generally much heartier, and meatier and cheesier than in Italy and frequently sporting some red color. And, if a restaurant's menu touts its sauce, it's Italian-American.
But restaurants need to serve what people want, and the menus are not static. These might often have pasta carbonara, fettuccine Alfredo and penne alla vodka, dishes born in Italy after the big emigration to America, but have become very American in interpretation here. Steaks, too. Americans love steak.
Similar to the Italian-American restaurant is the newest type, the Americanized Italian. These do not hew to the Italian-American traditions for the most part, and use more contemporary ideas and products from Italy, but the food is generally different than it is in Italy. These are often from a skilled chef who puts their spin on Italian dishes, or their notion of Italian dishes, and might use the Italian cooking philosophy as an inspiration. The quality of ingredients is usually high, and sometimes expensive. Italian descriptions are often used to portray a greater sense of authenticity or understanding, at least, even if the Italian is often mangled.
Restaurants that might be called Italian try to mimic how food is prepared in Italy, or in very capable and knowing hands, express the ethos of Italy and with Italian products when necessary. The chef is almost always from Italy or has cooked there. They know Italy. Italian can be in one its regional or local variations, and from rustic to high cuisine to creative. In the U.S., traditional and mostly authentic Italian usually features several dishes that are popular outside of Italy or popular in across a lot of Italy, especially the touristed cities and towns (e.g. cacio e pepe). Truly Italian food can be tough to do, and its appearance in America is actually somewhat recent. Tony May of the landmark San Domenico in New York was quoted in 2008 saying that "twenty years ago it was very difficult to reproduce regional Italian cuisine…..A chef couldn't get imported Parmigiano-Reggiano or buffalo milk mozzarella, virgin olive oil, prosciutto di Parma, or balsamic vinegar. Now, everybody can buy the finest of such ingredients, and it's made a tremendous difference in the taste of the food." But, even so, the way we eat in this country is different than in Italy, what customers want is not the same, and restaurants need to make money. "There's no point in being strictly authentic with an empty dining room," as Lidia Bastianich was quipped a few decades ago. That’s one reason why authentic Italian restaurants can be hard to find here.
In Italy, Italian food means all of different things. In this country, it can mean even more, and often items that are really more American than Italian.
The meat ravioli at the original Carrabba's in Houston