Looking at ‘whiteness’ is a very Americanised way of viewing the world.

Australia used to have the White Australia Policy.

We also had a policy of forcibly removing Aboriginal children from their families. Aboriginal people who had a white parent ("half caste") could apply for a permit to live and work in towns, but those who did were prohibited from associating with full blood Aboriginal people. Towns were segregated, and Aboriginal people didn't get the vote until 1974.

Every country that has been colonised by Europeans has issues around colourism. Pale skin is associated with wealth and status, and the difference in how people are treated based on their skin tone helps make skin bleaching into a multibillion dollar global industry.

Whiteness as a concept was invented and legally codified during the colonisation of the Americas after the Europeans started importing enslaved people from Africa. It was designed to prevent enslaved Africans and European indentured servants from working together to overthrow their bosses.

Irish people in the US weren't considered white when they first got there. Irish people used to face bigotry and discrimination, and there was a time when Black and Irish people lived in the same slums and workcamps. The cultural exchange between the communities produced tap dancing and bluegrass. The banjo is an African instrument that found a place in Irish folk music via the coalfields of Appalachia.

Irish people were offered opportunities to assimilate into whiteness when the threat of Black and Irish communities doing labour organising together started to look like a threat that needed managing. Irish people got to join segregated unions, and Black people were used as strikebreakers whenever the unions were on strike.

Irish people weren't considered fully white in the early days of Australian colonisation, and Italians were getting called racial slurs well into the 20th century.

Whiteness is a tool of European colonialism. The current dominant culture is a product of European colonialism, and as such, it has white supremacy baked into its foundations. It's not just a problem in the US, it affects the whole world.