There’s a ton of other reasons why the US is a bad baseline.
A) They let in far fewer immigrants per capita in the first place
B) The US collects incoming taxes on foreign income for it’s citizens, even if you lived outside the US while you earned it.
C) In some cases it’s harder for US citizens to work or live abroad. For example working holiday visas are only available to Americans in a handful of countries, where Canada has agreements with more than a dozen countries.