Pasta in Italy does not bother your stomach because pasta in Italy is made of ingredients that are purer as well as Italy has tighter food regulators, slower processing methods and even traditional cooking styles liking cooking the pasta all dente.
Traditional Italian pasta is also gentler on digestion and less likely to cause inflammation, unlike the highly refined mass produced pastas, that are often found in the United States and some other countries.
Italy also mainly uses high quality, non bleached durum wheat for making pasta.
Pastas made in the United states are often enriched with synthetic additives and also bleached, which can also be harder to digest.
And the European regulations also largely restrict the use of any pesticides like glyphosate.
And many of the American mass produced wheats are treated with pesticides like glyphosate, which are often linked to gut inflammation.
And traditional Italian pasta is also slowly dried at lower temperatures, which can sometime be as long as 72 hours, which helps to preserve it's natural starches and gluten structure, and makes it highly digestible.
Italians often cook their pasta slightly firm, also known as al dente.
Cooking the pasta to al dente or slightly firm, helps prevent the starches from fully gelatinizing and allows your body to digest the carbohydrates much slower.
And in Italy, pasta is often also eaten in smaller portions alongside of fresh, local ingredients and is often a single course.
Also if you do a lot of walking and stay active in Italy, it also keeps your blood sugar stable and digestion moving.