Earlier quoted context omitted.
Are those 1:1 comparisons? I know typically in the US salaries advertised are not exactly take-home pay, but before tax amounts, and is some places in Europe salaries are advertised as take-home pay.
Well it'll never be 1:1 due to differences in health care etc., of course, but those were all before tax from what I understood. Not sure how companies advertising take-home pay would work when your tax rate depends on e.g. marital status (at least in Germany it could be off by maybe a factor of 2 in both directions), which country/region are you thinking of there?
The one I used to work for had a real problem of developers leaving for the US on an internal transfer after 12 months, precisely because of the salaries.