You have to normalise by purchasing power and take the quality of life into account. My 60k salary in Poland gives me similar quality of life like 100k in Denmark and 140k in SF.
IT salaries here are much better than western Europe compared to other professions and it's not worth migrating.
I've interviewed for jobs in Netherlands, Belgium, Denmark and Germany and the highest offer was 75k € for job in Brussels region.
According to online calculators thats 40k take home salary with housing and services at least twice as expensive. My 50k € Croatian salary leaves me with 33k net with vastly better quality of life.
Why are western Europe's developers paid so little while living in much richer countries?