I always laugh when I hear this. You don't have to imagine Italian food without tomatoes, you could just go to Italy. This whole idea that Italian food uses lots of tomato sauce, or tomatoes in general is a very italian-american thing. There's tons of Italian food, I might even say the majority of, that doesn't use tomatoes. It's really only southern Italy that uses tomatoes. That's why it became so popular. During the migration to America, it was mostly southern Italians (Sicily, Calabria).
Like this meme, the idea that Italians use tomatoes in everything is mostly an American thing.
Traditionally spaghetti is a side dish and while true can be served with a tomato sauce, it's nothing like you see in italian-american dishes, and more commonly used with lighter sauces.
And a margherita pizza, while very much a thing was really only invented at the end of the 19th century and is just one of many styles of neopolitan pizza.
My point isn't that they don't use tomatoes in Italy, it's that this idea that Italian food = heavy tomato sauce is more of an American thing.
Go to Italy and ask for spaghetti and meatballs and see how many restaurants actually have that on the menu.