Parental leave for fathers

In Norway fathers are expected to take care of the newborns and the government has instituted regulation to that effect Protected content
As you can read in that article, there is some controversy around that. Some scholars seem to think mothers are more fit to take care of children.
Obvious additional questions to this debate are;:
1) How can anybody establish what is “best for children”? What would be the KPIs (key performance indicators) for good parenting?
2) If one of the reasons we have children is that they make us feel happy when we take care of them, has a mother more right on happiness than a father?
3) Is parental attention really all that important, since some higher classes seem to do well with kids being raised by a nanny and going to boarding school?

(For those who are wondering about my opinion: I like that Norwegian idea and I firmly believe there is no “silver bullet” in parenting. It is up to the parents to decide what solution is best, given the individuality of each child and all the other factors that come into play)