Milton Friedman's negative-tax proposal was intended to replace the "War on Poverty" policies, which in turn were enacted out of a genuine fear that the poorest would be unable to support themselves.

Huh? As far as I know, the "War on Poverty" policies weren't motivated by the fear that the poorest will be unable to support themselves (after all, they managed to do so throughout all the preceding times). They were motivated by the optimism and can-do attitude -- the economy was growing very well, the middle class was booming, the progress towards the shining future was inevitable, so the Federal government should help the less fortunate get on the shining-future bus.

What we see in Germany is mostly the latter, and is thus of little practical consequence.

One of the most influential politicians in favor of UBI in Germany is Dieter Althaus from the CDU (the right). I also don't think it makes sense to see billionaire Götz Werner as wanting to give his consituents free money for votes.