The best explanation I've seen is that in countries with high economic insecurity, people are motivated to work at lucrative careers with low barriers to entry, despite their lack of inherent interest. Programming is top of the list almost everywhere. The survival instinct surely is egalitarian.

But in countries with less economic insecurity this motivation to work in a field without an inherent interest simply isn't there. Perhaps this motivation is different across genders in wealthier countries (men are more likely to go into fields they don't like), or men simply like technical fields at higher rates.