Regarding American Italian food, My Italian American Jersey City ancestors were fantastic cooks. They made all the classic American Italian dishes, and the food was fantastic. Think everything that looks delicious on The Sopranos. Cuisine evolves, and ought not be represented by its worst iteration (Olive Garden).
Likewise, I grew up in San Diego and had travelled to Mexico at least 100 times by the time I finished college. Good Mexican food in both places, but overall better in SoCal than Mexico. IMO anyway - the evolution of Mexican food where I grew up was simply better than the home country. And of course we aren't taking about Taco Bell, but great restaurants and tacos shops owned for generations by Mexican American families.
One more. Pizza people seem to like to claim that the farther you get from the origin pizza, the worse. Argument goes "it's fine, but it's not X (New York, Naples, Hartford, etc)." I'll argue that the best pizzas I've ever had were in the San Francisco Bay Area. Plenty of Italians, close to great ingredients, and a region with incredible talent for breads. Nope, it's not Naples or New York, but nevertheless you can get GREAT pizza in San Francisco, better IMO.
Seattle, on the other hand, has horrid pizza. It's slightly improved with the certified wood fire movement, and then the importation of the SF style (Tom Douglas Serious Pie etc,) but by and large Seattle is still a lousy pizza town.