Japanese food and Indian food are as different from each other as Indian food and Italian food.

I'm not sure how you arrive at that opinion. Take the example of Punjabi food. It's heavily based around ghee and dairy. Does anything in Thai cuisine use butter except European style pastries?

The only major similarities I see uniting the national cuisines you listed (not regional ones) are things like curries and rice. The former arrived in Japan with European influence (where it's also common in colonial countries) and the latter isn't a feature common to all Asian cuisines (e.g. Mongolian).

Asian countries developed with more overlap in basic ingredients, cooking techniques, and historical influence networks than Europe did. Historically there were 3 influence zones in Asia. There is a lot of pickling, fermenting, salting, drying. In Asia of these techniques were more or less unified. Fish sauces from different countries are Pepsi vs Coca-Cola level of difference.

> Polish and Spanish is closer to each other than to most other asian cuisine.

I'd say Polish has a lot of similarities with Asian cuisine. Sure, both have stews and sausages, but flavor profiles are very different: acidic vs sour.

I won't be able to tell difference between gyoza & wonton if they shaped the same, but surely I can tell difference between ravioli & uszka. Uszka is IMO closer to any dumpling from Asia than to anything European.