You end up with the government deciding how much bread each person needs, how much the bread will cost, how much to pay a person so they can pay the defined price for the allocated amount of bread, etc.
Either utopian claims of an AI and robot-powered future are right and we don't need money because you can just have what you want, or money and resources will still be scarce and we will continue to compete amongst ourselves for resources.
2) America in 2026 is not the USSR in the 20th century, so even if they did, our circumstances are very different from theirs.
3) UBI was only the first suggestion; you completely failed to address the other and then jumped to a black-and-white conclusion.
The general thrust of my proposition was that people shouldn't have to submit to an artificial system of manufactured competition and unnecessary "productivity" in order to access goods that are objectively abundant. When people realize that and make the necessary compromises, they won't have to worry about shipping useless AI-assisted slop for "income security" and can focus on using AI to build consequential and useful software.
Please do not get bogged down in whatever kneejerk anti-UBI thought-loop your misaligned amygdala is screaming at you.