Couldn't this largely be explained by their importing huge amounts of low-income people?
It does in Canada, I think that’s what he meant
https://tradingeconomics.com/canada/gdp-per-capita#:~:text=T...
https://tradingeconomics.com/united-kingdom/gdp-per-capita
(Click the button to check the 25 year view.)
https://www150.statcan.gc.ca/n1/pub/36-28-0001/2024004/artic...
"another respected data journalist, John Burn-Murdoch, calculated that without London, the UK would be poorer, in terms of GDP per capita, than even the poorest US state, Mississippi."
None of this changes the fact that US software engineering salaries are a poor comparison to use to illustrate wealth disparities between the US and other countries, as they are an outlier.