Maybe it's just me but I'm getting tired of UBI being put forward as a realistic answer to technological displacement of workers. The most immediate problem would be getting it through legislatures without loopholes that undercut its purpose as a replacement for all other redistributions. That simply never happens, particularly in the US.

The next problem is that no one seems to appreciate how incompatible it is with open borders in a world of nation-states. The latter is particularly telling since advocates of UBI are often advocates of less restrictive immigration across the world, yet they don't seem to see the problem. It's an indication of how ungrounded the discussion about UBI is right now.