I think we started out by admitting that job retraining is hopeless in the long run because any job you could retrain a coal miner to do will not exist soon. We will have more and more people with no job prospects because of automation. A UBI is one way to see that they don't starve.

Of course that brings up another problem: The poor having lots of kids, all with equally poor prospects other than becoming cannon-fodder or criminals. Maybe long-term birth control has to be heavily pushed in the free medical care?