> The first is that we automate everything. This is implausible, but let's consider what would happen. Well then necessities would be free, because there is no labor cost to produce arbitrarily many solar panels or skyscrapers or mine asteroids to get unlimited raw materials etc. So then you don't need taxes because nothing costs anything.
Well, you still have to pay for the energy (to extract raw material and transform it into final product, and move final product into your hands). So unless we assume energy cost is 0 and raw materials are not scarce, the final product has a cost, and a price, now my understanding is that if everyone uses dark factories, the margin would go down, and so the gain per "company" would drop too, hence the limited tax base.
My guess is from the 2 ends of the spectrum that you listed, we are moving from "there is still work you need people to do, and then they do that, and still have jobs." to "we automate everything". And as we move to the "we automate everything" end of the spectrum, the number of jobs lost would increase, the taxes collected (VAT, income, capital gain, etc.) would decrease (assuming the current tax system) and yet people (employed or not) would still education, health care, social security (retirement).
If we do not change how we tax things, I do not see how we would sustain a society where the majority is materially (gizmos) rich, but financially poor (no job, no retirement, no social security, no education).
While dark factories keep producing high volume of gizmos for next to nothing...
I am curious how we can manage that transition, which I believe could happen way faster than politicians can move.