[romland]

It might be a Nordic thing? I'm from about the same era (but Sweden) and when writing documents like that, I'd also always use 'she'.

[Maxion]

Finnish has no gender pronouns. Everyone is a hän. That’s why Finn’s often mix gender pronouns when speaking.

Not caring about your gender is baked into the language.

[defrost]

I'd say that assuming 'he' might be a US thing - 42 years ago when I was in Australian university math | comp sci classes a third of the students were female as were staff.

Even then I routinely used 'they' when writing about people in general, authors I had not met, etc. as there was a good chance they weren't male.

[runlevel1]

It used to be taught that the singular "they" was ungrammatical. (Ironically, the singular usage predates the plural.) The rule faded in other parts of the Anglosphere a bit earlier than in the US.

[1]: https://en.wikipedia.org/wiki/Singular_they