The US Border Patrol encountered over 100,000 attempted illegal crossings every month in 2021. It's estimated that each year somewhere between 500,000 and 1,000,000 people cross the border illegally without being caught or overstay their visa. There are nearly 50 million foreign born persons in the US total, about double the rate per capita of Europe.

Europe is on the same demographic trajectory - the current statistics put Europe where the US was in the 1990s. Focusing on unions as an example, since the 1990s, the US has lost approximately half the union membership rate in the private sector. This is in part due to immigration and in part due to offshoring, both mechanisms serve to weaken the power of the domestic worker.

You may be right that "race" isn't perfectly well defined, but socially and culturally it does exist and it plays a role in how people act. For example, even in highly diverse and progressive places you find clear racially segregated patterns of residence, with major downstream effects in areas like education, employment and healthcare. This is true in both the US and Europe. I'd be curious to hear your thoughts on that phenomenon.