So 13% native black population, a higher percentage native born Hispanic population, multiple generations of multiple different Asian cultures, these dont count? Why?
All your metric does is demonstrate who began allowing immigration first.
US is 76.3% white compared to Canada's 77.7% white. Still pretty similar. Actually, US's numbers are from 2019 but Canada's are from 2016. Canada's percentage should be lower than US's now, given the difference in their annual immigration numbers.
I think 76.3% white is misleading because, while the U.S. Census Bureau counts hispanic people as "white", basically no North American's intuitive model of race or ethnicity would count hispanics as white. Which is why the Census is always careful to break out non-Hispanic white.
The real comparison is non-Hispanic white to non-Hispanic white, where it becomes ~55% to ~75% or so. Hispanic people in the U.S. are easily visually differentiable, most often have one or more languages aside from, or instead of, English and come from cultures that are markedly different than mainstream U.S. culture.
It's getting into the weeds a little, but there are also likely differences between local vanquished populations, immigrants and their descendants who arrive voluntarily by air/sea, those who arrive voluntarily by land and those who arrive involuntarily.
Canada and the USA are close overall, but Canada's immigrants are much more likely to be educated professionals than those coming to the USA. And since Canada never implemented widespread slavery, there really isn't an analog to the experience of black Americans. I think that is a very big factor.
All your metric does is demonstrate who began allowing immigration first.