>And even if you're okay with impoverished seniors, burdening their children of child-rearing age with a new financial obligation doesn't raise birth rates.

It's better than burdening them with that and FICA taxes and the devaluation of the USD, which are also a financial obligation. The burden can be split amongst children, incentivizing raising more, or parents can opt out of burdening their children by going on a very, very long fishing trip.

The government mandated wealth transfer from young to old is obviously unsustainable, in all countries around the world. It is predicated on the assumption that people will "naturally" opt to raise a minimum of x number of kids (economically productive ones), yet the system is most beneficial to those who raise no kids.