That's fine, no problem.
> Yes. But I don't see a problem with that (I mean you can still estimate costs and offer a price based on that).
It's not a problem in a capitalist or even a fully market-based system. My original point is that the information prices obscure might be functionally useful in a non-capitalist system.
> Same applies to labor though. e.g. it took the worker N hours to make it, he used up X amounts of calories to do that, his dormitory bunk costs Y etc.
Yes! There's some amount of cost to derive this information, and there would be thresholds where it just doesn't make sense to collect (or feasible). My point is that we actually do know the costs of various forms of labor and the amount of resources used in things, we just happen to throw them in the trash with each transaction.
> So what, though?
The information we throw out could be useful in scenarios other than "well, that's the price and that's all that matters." One example is the ability to price in known externalities of various resources (or the processes they go through). If you know fossil fuels burned at-scale are "bad" and you know exactly how much fossil fuels it took to build some product, you can immediately tax some externality-cost price amount of the product at point of sale.
In effect, this limits the scope of "economic planning" only to pricing externalities and lets "markets" (not really, because profit is gone, more like "distributed production") self-organize as a solving mechanism for those externality costs.
That's not to say you can't still use planning for bulding a freeway or a bridge or something, but fully planned economies are a beast of their own and I'm not a fan. This is a way of transforming markets into systems that operate within humanity's collective knowledge of the side-effects of production in ways that governments just can't handle.
