> efficient

Economists and market fundamentalists keep using that word. I do not think it means what they think it means.

Economists know what words mean.

Efficiency can mean a lot though. It depends on what you want to maximize and what to minimize.

They also know that free trade is superior to planned economies, soviet union style.

Planned economies haven't worked in the US, either. For example, before Reagan deregulated the airlines, the airline schedules, routes, and fares were set by the FAA.

The result is airliners often flew nearly empty.

Once that was deregulated, a titantic shift occurred, such as the emergence of the hub-and-spoke system. Airplanes have been packed since then.

The FAA bureaucrats proved incapable of efficiently setting routes, schedules, and fares.

In the 1970s, the Energy Department decided a gas station's gas allocation. They did this for every gas station in the country. The result was simultaneous gluts and shortages of gas. Reagan deregulated that with his very first Executive Order, and the gluts, shortages, and gas lines disappeared literally overnight.

Planned economies just don't work.

You mean centrally planned? Companies plan decentrally.

At what level of regulation is a market free? As an example of a hard to capture word.

Regulation to prevent use of force and fraud, and contract enforcement, and dealing with externalities.

According to that definition we don't have a free market and in theory we will never have a free market. Which is ok. The idea of a free market is an ideal to strive towards. The problem with the idea of a free market though is that in practice it is used as a political weapon for the sake of specific interest groups rather than to the benefit of everyone. No attempts to make markets more free are visible.

People argue against land value taxes and carbon taxes. These policies are intended to reduce externalities and reduce the amount of force necessary to live a good life. Imagine all the wars fought because we have inefficient land allocation schemes or all the damage caused by climate change leading to loss of soil fertility in specific countries and the following refugee crisis. In a hypothetical free market wars would be pointless because you can always get what you want through mutual agreement, for a fair price and without any violence.

Who decides when "dealing with externalities" has been done in a proper way?

The very word "externalities" and the state of the global environment don't inspire much trust in the efficient management of "externalities" through capitalism.

Pointing this out doesn't mean that I am a socialist ot communist, I don't like this this kind of black and white thinking.

Wouldn't "efficiency" mean that we use natural resources sustainably?

That's not happening as far as I see.

> Who decides

The government, of course.