In some countries there might be valid concerns that the wealth has not been acquired legally. If the wealth has been acquired legally, however, it is not obvious why people should object to having wealthy people live among them. Is it just envy?

It seems to me that the movement of people between countries (or tax jurisdictions) is not a trivial matter. I think it would be beneficial for most people in Australia if we had more fabulously wealthy people living in this country and spending their incomes here, even if this does make the distribution of wealth in Australia more unequal. If concerns about inequality in the U.S., for example, result in imposition of additional wealth taxes, inheritance taxes etc that will encourage more wealthy Americans to consider moving to Australia, in my view that will be a plus for Australia.

Yes, there are some people with high levels of income that may have dual citizenship. But that’s far from the norm, and would almost certainly have a negligible effect on the data as a whole.

Even if you account for the undoubtedly lower end of the spectrum (as you, to your credit suggest), this doesn’t mitigate the relevance of income inequality. Rather, it suggests that we ought to have an implicit assumption that things are much worse than what show up on official statistics.

Finally, the Wilkinson conclusion is nonsense. If you are taking a neutral moral position, then you should account for everyone. So you include migrant workers, which may make the lower end of the ‘legal’ spectrum seem relatively wealthier. But they major effect would be to make the very top of the pyramid seem even more disparately wealthy. Which is, of course, the real issue with inequality.