My working hypothesis is that software-defined Turing-complete automation is qualitatively different from special-case automation. It permits the rapid reconfiguration of general purpose machines with software, which is cheap and fast to produce in comparison with pretty much any physical system. Combined with simulation it allows for very rapid iteration.
You can in many cases effectively design something and then just hit 'print.' Some human intervention and assembly and some custom work is usually required, but the quantity is far lower and the skill level far higher than in the past. In the end you need a small number of highly skilled employees, not a large number of low-skill ones. The conventional 'worker' is obsolete.
Compare one-off factory tooling set for stamping out one part with a 3d printer, for example. The 3d printer is what the future looks like.
The alternative to a universal basic income here would be something like the world depicted in The Hunger Games series -- tiny super-rich walled totalitarian city-states presiding over a majority that has regressed to 19th century or prior standards of living. I'd personally consider this to be a new dark age.