A number of the “No Robot Jobpocalypse” arguments seem to hinge on the idea that as productivity increases, the costs of goods and services will approach zero.
But this seems based on the assumption that resources are effectively a function of labor. However, if base resources are largely fixed after some level of labor (e.g., there are only so many iron atoms in a volume of dirt), and there are other potential uses for those resources than feeding the proles, then the laborers must competitively bid for the resources.
In that bidding, they may have to bid with someone several orders of magnitude more productive than they are (either due to owning the robots or just being that much more skilled/productive). What guarantee is there that, even as the price of goods produced from the resources decreases overall, they are not bid out of the reach of the low-marginal-production workers?