Raising children is an example of "unpaid labour"?
That's how human families units worked. If someone has to go out to do work, the other parent got to look after the kids (with some help from the previous generation once they had got rid of theirs). Traditionally this was the wife (woman) but as work was heavy manual labour and mothers less able to do it than fathers (men) on average. This was just how physical ability worked - it wasn't the patriarchy that deemed it to be the law.
Things continued like this until quite recently. Firstly because the industrial revolution opened up many more jobs that were more suited to women, secondly the World Wars mean demographics changed (especially during the war) so women had to work. But mostly because people wanted more stuff (bigger house, BMW on drive etc) and so women went out to earn more money.
Despite the liberation of women this has brought about, you could question how well it's worked overall. Within the last 30 odd years, women have gone from making the choice to work to needing to work as all the extra money has been spunked on more expensive housing and German motors. The family is not any financially better off than when Dad worked, Mum stayed at home and Dad's wages covered a 3 bed semi and a Ford Cortina and a decent life.
Now they have a 4/5 bed executive slave box on a toytown estate with a massive mortgage, BMW on PCP and are stressed because they can't make ends meet. How liberating is that?