If they want to attract more tech workers they really need to up their salaries. People might go for maybe cultural reason or whatever but that pool is not enough to close the gap is guess.
Having a good salary is important but the work-life balance is just as important, if not more. I lived in Japan for a years (not as a dev, am now); I can make do with a lower salary due to healthcare being mostly sorted (you pay 30%, government pays 70%) and a good standard of living (better than London IMO), but I don't want to work absurd hours and deal with a toxic working culture, alongside a low salary.
I've met many talented women in Japan via Meetups and Women Who Code Tokyo and there's definitely no shortage of great developers. People just want a fair work-balance and an honest salary, which they are more likely to find at a gaishikei (foreign-run company)
I was thinking of maybe work a couple of years in a Asian country when the world starts opening up again hopefully somewhere in 2023~2024. So that I why I did some minimal research on salary.