@RobertoArchimboldi
if i understand correctly, your distinction between value and price corresponds to marxs distinction between use value and exchange value. while a things use value is just a consequence of it being used in some way, exchange value is a feature of something specific: not just any thing, but a commodity, and not in just any society, but in a particular form of society, capitalism.
marx did not assume that things simply have prices, as a natural thing inherent to them like their mass or their chemical composition. his project in "capital" was to describe how capital functions, and more importantly how it destroys its own basis for existence. he didnt just criticize capitalism for empowering a small class of owners, but for the very way that things become commodities and are used to make more commodities, made into capital.
marx conceived of communism as a society in which the "law of value" would be abolished, in which commodity production and the system of wage labor would be just as outdated as slavery and serfdom. in other words, all those things that are now commodities and capital would cease to have their price and return to being mere things.
without a state to beat them, a capitalist to starve them, or a landlord to rob them blind, every person is free to engage in labor to the best of their ability, and free to engage in rest to the extent of their need—and then some more, since the end of the profit motive would make a lot of labor completely pointless. one thing that would likely take up more time is collective decision-making.
if a bunch of people think that building a railroad would be a useful thing to do, theyre probably going to try to do it. if this comes into conflict with several sunny spot enjoyers who object to the plan as presented, thats a problem. in capitalism, this could be a legal battle between local private property interests and some corporation formed by the state to build a railroad. in communism, this is a deliberation between groups of people, not divided by lines of class or birth nor by offices of power, arguing with the aim of reaching consensus.
attendance at these deliberations would be voluntary, so there would absolutely be a bias in favor of people with more energy, patience, confidence, communication skill, and persuasiveness. this is hard to compensate for, but i think there should be an emphasis on accomodating for the needs of disabled people, children, and elderly people, to make their voices heard.
the kind of coordination and planning necessary to have an industrialized society is pretty huge. indeed, it didnt exist until capitalism did. that is why marx understood capitalism as a progressive step compared to feudalism, in that it set up the conditions that make communism possible. among these conditions are what he called the "socialization of labor".
whereas on a family farm or in domestic manufacturing, the peasants of old europe only ever worked in family-size groups more or less, capitalism brought with it mass manufacture, and then mass industry, and created structures through which decisions were being made collectively on the level of hundreds or even thousands of workers all at once. it isnt the capitalists who busy themselves with the nitty gritty of operating a business, they leave that to their managers, their foremen, and ultimately to the workers themselves.
marx reasoned that if thousands of workers could act together on the orders of bosses, they could organize and learn to act together of their own collective will. when capitalism created the modern working class, it created something that is capable of everything capitalism has done and better, and doesnt need capitalists to do anything. this is why marx thought that industrial production wasnt just compatible with communism, but that it made communism possible.
at this point we are no longer able to entirely prevent the collapse of the biosphere. we may be able to mitigate its effects and minimize the number of lives lost, and the biggest obstacle is getting rid of capitalism, the system that caused this mess. as i see it, there is no force on earth which is capable of accomplishing this except a self-organized mass of people that spans every continent. that kind of connection and coordination is a product of the capitalist world just as much as the crisis itself is, and will certainly require industrial technology.