Have you heard about the last century? A few governments did that. You had to stand in line for food and your basic goods.

No they didn't. In the USSR, for example, not working without a valid reason was literally a crime (look up tuneyadstvo).

Great point! But for how many weeks will you enjoy your UBI before the rulers say "Okay, now that we're paying all of your salaries, it's time for you to do the work we need. Off you go to build the railroad or the giant dam! Here's a pick-axe."

If we are able to fill our storefronts with magnificent AI creations for cents on the dollar, would that be profitable enough for the producers to pay enough tax to cover UBI? Producers would still face pricing pressure to lower margins to eat up all those productivity gains. Every path forward seems very uncertain

I think you didn't understand I didn't mean tax income literally I meant tax everything ala wealth. No private ownership beyond your home and a set of vehicles for transport.

Now if you are saying there won't be any wealth in the post AI era, sure there might just be power or energy then we will tax that, 90% of energy generated is owned by populace they get to use it sell it or whatever.

Imagine if humans had control over energy that machines/AI needed for production, then can't they just ask AI to do work to feed, cloth and help humans?