Producers and buyers have different interests. One wants to sell dear, the other wants to buy cheap. On the whole, this balances out by itself. But there also has to be a conscious regulation that stands above both.

An example:

The baker offers his bread in public. He does not offer it to one single person, but to everyone. And everyone has a right that no one cheats them. So a public office may fix prices and check the goods.

The more important reason:

Big industries depend on distant markets and circumstances. Those who work in them cannot see how all this hangs together. So there must be general care and direction.

Two extremes:

The one is complete freedom of trade and business. The other is that the state decides the work of everyone. That is how the pyramids in Egypt came about, without the workers’ own will.

Self-interest likes to call on freedom against any regulation. But the blinder it is, the more it needs regulation. Otherwise the dangerous crises last longer, until everything balances out by itself.

Summary: On the whole, the economy balances out by itself. But it also needs conscious oversight. This protects the buyers and eases the crises.