Also, they're saying: "At least half of our Tweepforce will be women". So they're suggesting that more than 50% of one gender is ok, as long as they're women.
Maybe people want to live for themselves because having children in the current economy is too exhausting? I'm pretty sure that if people could more easily afford everything what's required for having children they would be more willing to have them. Sure, some people still don't want to have a responsibility but I think plenty of people want children but just can't afford them.
Currently I think it's quite expensive (for locals). E.g. bedroom + living room costs > 3k PLN in Cracow, and probably more in Warsaw. At the same time junior dev can earn about 5-9k PLN net. My non-dev friends often are not even able to live in Cracow.
We don't have such a law in Poland but we have a nice culture of posting salary ranges in IT offers. It's very ubiquitous on boards, Facebook, Slack channels, etc. We also have a (very popular) board where it's required to share a salary range (you can take a look on nofluffjobs.com if you are interested, it's not an ad, I just love the idea).
In Europe I think it's far less common to be fired in the first place, I actually know zero people that was ever fired (but I'm not saying that it doesn't happen, I think it even happened recently at Klarna).