The economy is not primarily about the adjustment of capital investment across industries and firms, but about the determination of which industries and types of production will exist—and who will be involved in this future production.
In terms of economics, what currently is should be of very little importance: what matters, and that we should seek to understand, is the process that brought it about and that will create what will be in its place.
It is possible to determine in terms of money prices the sum of the income or the wealth of a number of people. But it is nonsensical to reckon national income or national wealth.
Robots are not fundamentally different from other labor-saving innovations, and there's no reason to believe increased innovation will lead to mass unemployment or mass poverty.
When a parent leaves the work force to focus on parenting, this shows up in government stats as lower employment and less consumer spending — suggesting a less productive economy. But that's not what's going on at all.
It's impossible to calculate the cost and benefit immigration without considering psychic profit and loss. And the government definitely is in no position to make any calculations at all.
Hard-left "democratic socialists" think they figured out how to make government planning possible: use prices. But there's a problem in their argument: prices are impossible without markets.