Melodi
Disaster Cat
The tomato sauce is a relatively recent thing. It is debated if it was invented in Italy by a chef trying to make a dish in honor of some VIP (a king or a prince maybe), so with tomatoes and basil, it was green and red like the colors on the Italian flag. Or was invented by Italian-American immigrants (like corned beef and cabbage with the Irish immigrants)? I don't know if that has ever been solved. But I do know that when we were at a traditional restaurant in Naples, you could get pizza. Fired in an oven that looked like the one I'd spotted and identified at Pompeii a few hours before. But the pizza crust was extremely thin and crisp, and the sauce very sparse. Our hosts said this was normal in Italy.and don't forget you can put a white sauce on your pizza instead of a tomato based sauce. Friend was just in Italy, up on the border with Austria and Switzerland and was horrified to find out that the shops in that particular region didn't use a tomato based sauce.
Even outside of Italy, I had noticed that most pizza in Europe outside of Pizza Hut was almost always this crisp, thin crust. Even the pathetic attempts we had heated in England and Scandinavia. Things have improved over the years regarding decent pizza outside of Italy, but it still tends to be, as Nightwolf described, "A cracker with tomato sauce on it." At last, the Italians use real cultured or fermented dough, real sauces (including white sauce), real toppings, and old-fashioned, 2000-year-old style ovens when they can.
So native to Italy or Italian America, the Italians take pride in making edible versions today. The white sauce on a flat bread cooked on a stone hearth (with cheese and meats) probably goes back in some form to the Roman Empire anyway.