Well, right. Think of the canned and other non-perishable Italian foods that make it to the US: San Marzano tomatoes, cannelini beans in jars (not cans), tuna in olive oil, extra virgin olive oil, dried porcini. All of these generally taste better than their American counterparts - although not by a whole lot. So if you were to make a meal out of Italian processed foods and then make the same meal out of American processed foods, the Italian version would taste a bit better. Then add cheese to the equation -- good cheese in Italy is trivially easy to find and nowhere near as expensive as good cheese in the US -- and it becomes obvious why even low-end restaurants in Italy serve better food than similarly-priced places in the US.

(Although I think it's not just the ingredients. There's also a certain ethos of making things from scratch, such as the fagioli we had in a pizza joint. Especially at sit-down type chain restaurants here in the US - think Denny's, PF Chang's, Cheesecake Factory, and the like - everything is pre-made and just warmed up and prepped. It's very efficient, but tastes nowhere near as good as a from-scratch meal.)