Not only that, when Italians, Greeks, Hungarians, and other Slavs first arrived to the US after World War 2, they weren't considered White. while scientific racists at the time believed that Mediterranean people were lazy by their nature, I found it weird when reading about the founding father drafting the constitution being heavily inspired, and learning from, the Romans and the Greeks, you'd expect at least the founding fathers and future US government officials to admire, if not at the least bit respectful, of the Italians and the Greeks, but this never seemed to be the case
So like, why?
The argument of european immigrants "becoming white" is essentially completely fabricated. The US was an explicitly white nation for a portion of it's history (free white person[s] ... of good character" in the Naturalization Act of 1790) and we can judge who was "white" by who was allowed citizenship under that act. Russians were all given citizenship in 1867 when we absorbed the Russian American colony. Hell Philip Mazzei, an italian, was literally a founding father.
The myth of becoming white is an academic fantasy that has almost no basis in history. It's almost never been more clear than one of the major claims to its existence in that article is a copper mine in Utah.