The poorer the country, the more women work in traditionally male fields. In Bolivia and in Peru, I was surprised to see many women working in construction and driving taxis.

You saw it in the US during the two world wars. Women got more rights and there was some interesting propaganda encouraging women to work.

https://en.wikipedia.org/wiki/Rosie_the_Riveter

If not for the war or other legitimate reasons I'd assume a preponderance of one demographic doing a specific job as likely a bad thing. I'm surprised it'd be wishful thinking.

Both. But mostly the war.