>Are there any countries that could serve as an counter-example? That is, has numerical parity between men and women in tech ever been achieved without implementing targeted diversity policies?

As far as I know in poor unequal societies women go more to STEM careers[1]. I'd think that's because you don't have the luxury to choose to study something that won't pay well after your parents made the effort to put you through university.

[1] https://www.theguardian.com/guardian-professional/2015/jun/2...