3 months of leave or a small welfare payment are not sufficiently compelling alternatives to a career. Pay them at the level of a career and see if that changes the numbers - I feel like at least some people would be interested in that. (Say, median national income? Spitballing here)

The countries that do try seem to fall short of actually replacing even a few years of serious career work and offer no way to go back to that career after taking care of children for a while, so you just need to do that.