It's different not just among countries, but within a country. Good developers in big cities in China can make close to 100K USD. There aren't many, if any, go

It's different not just among countries, but within a country. Good developers in big cities in China can make close to 100K USD. There aren't many, if any, good developers in rural or extremely poor areas. Most of them move to technologically advanced urban hubs. This normalizes the differences a little and still make comparisons somewhat valid. At least less different than if you were to look at country-wide demographics.