In a free market, as factories compete for the acquisition of copper and steel, they create scarcity and abundance in these markets and the prices allow copper and steel makers to compete for the resources that go into making them. A central planner is completely in the dark about this web of preferences and opportunity costs of trains, cars, copper, steel, labor, capital, and land. Without prices, there is no way to calculate how to allocate these resources to produce the optimal products, and the result is a complete breakdown in production.
