I think there is an assumption here that the corporations will not simply pocket the profits from automation. It's not like you pay less when you use the self checkout at the grocery store.
There's a huge open question of what we're gonna do when automation crowds out large numbers of jobs, and that's potentially a significant societal shift. But right now we've already got human beings doing jobs effectively as robots, and already not creating real human interaction.
Personally, I'd rather be giving a UBI to those people for going off to, I dunno, create art or go on hikes and write about them or whatever it is human beings do when they're off being human. That might let me have some real human interaction, not a forced moment of intersection while they're just trying to get me my groceries so I can be on my way.