Norway has > 800x the oil reserves per capita of France and has not gone through what you could call a political crisis over the past few years regarding aligning the spending level of its welfare state with the economic and budgetary realities, with years of protests and riots, some of which are still ongoing. In the face of this it's quite a bold move for France to go from zero to 28 days for the sake of benefiting gender norms and family relationships in the long-term.
Norway, a rich country of just 5 million people, cannot be used as a comparison without noting all some of the budgetary context. Not just in this discussion, but more broadly on HN. If you're talking about something relatively budget-neutral like say 'same-sex marriage should be able to adopt children, just look at XYZ (e.g. Norway), it works just fine', that's alright. But if you're saying or implying something which has a lot of costs involved like 'fathers should get at least 4.5 months of paid parental leave as a rule, not an exception, just look at Norway' then you can't just leave out cost from the discussion, it makes no sense.
Obviously all of us would prefer long-term paid parental leave, arguing it's nice to have adds nothing to the discussion because there is already universal agreement. Arguing it's worth having, is an entirely different and much more meaningful discussion, but it cannot be be had without weighing the pros against the cons, the biggest one is cost.
And I say this coming from the Netherlands, an also quite rich country that I'd love to see as a model for many other countries. But such discussions should include budgetary context, among others.