I think you understated the similarities between Americans and Irishs / Italians, and understated the differences between Americans and Hispanics / Muslims. Not sure whether you did this intentionally, but it is so obvious that Americans / Irishs / Italians are part of western culture, they have differences, but they belong to one big group. On the other hand, Southern American / Middle East belong to non-western culture. The latter is even worse, it is anti-western culture. When you look at the countries, US / UK / EU countries are similar, but Southern America countries are different from US / UK / EU countries, and Middle East countries are extremely different. Did you intentionally blind yourself?
Also, we lived in a different time with two important changes: 1. welfare state. 2. far-left ideology (multiculturalism, post-modernism, etc.) becomes norm