There is a huge range of expat salaries/packages across all disciplines and nationalities. I think some of the top end ones are pretty obscene but heck, if the company will pay it, why wouldn't a person take it? Save enough to retire early and enjoy it.
However I do think (from my circle of friends) that more and more single people/younger couples are coming here on lower salaries, local packages, etc. New jobs (new homes, new lives?), rather than just "postings". It's not all about money.
(Xref the discussion about PR.)