Question: Why don't Italians eat Spaghetti & Meatballs?
By: Rorschach
Published: September 27, 2010

Italians eat spaghetti and they eat meatballs, but never the two together. And yet the dish is "classic" in the US, apparently begun by Italian immigrants in NYC. What gives?

Answers:
Chris Paulk

Pasta was considered the poor man's bread. It was eaten in the field with out sauce. Spaghetti & meatballs came about in America much later.
From The Nibble;
"Dry pasta was the food of the man in the street. Since its introduction, it was eaten using the hands (remember its origins as a soldier’s field provision). It was sold as street food by vendors called maccaronaros who cooked it over a charcoal-stoked fire; it was eaten on the spot with bare hands, plain or sprinkled with grated sheep or goat cheese, no sauce. The wealthy, who did not eat with their hands, ate fresh pasta stuffed and seasoned with cheeses and meats—lasagna-type preparations that had been around since Roman times and the newer dumpling styles from China. Around 1700, one of the chamberlains to King Ferdinand II thought to use a fork with four short prongs to eat the long strands of cooked dried pasta. After that, eating long “strings” of pasta became a common practice. It enabled pasta to be served at banquets all over Italy, and from there to all of Europe and the world.
The next big advancement occurred a hundred years later, with the marriage of pasta and tomatoes. Although yellow cherry tomatoes had been brought back from the New World by Christopher Columbus at the turn of the 16th century and then by Hernando Cortez in 1529, they were used as a houseplant. (The Italian word for tomato  is pomi d’oro, golden apple.) The fruit, a member of the nightshade family, was viewed as poisonous. Lean times drove peasants to try the fruit, with happy consequences. The first documented tomato sauce recipe is from 1839.
Spaghetti and meatballs is a dish unknown in Italy, but probably had its origin in several baked Neapolitan pasta dishes served at religious festivals such as Carnival and Christmas. (Naples is the capital of Campania.) Remembering that meat in Italy is costly, these dishes used meatballs the size of walnuts—unlike the American version that used meatballs the size of eggs—and also included other ingredients as ham and boiled eggs. The large portions served, and heavy seasonings of garlic, oregano and hot pepper flakes, are American developments."
Curt

For the same reason Mexicans don't eat Nachos. Spaghetti and meatballs are an American thing.