But off the top of my head, Mel Dragon has a particularly good set of answers. You might ask to take a look at her test. Most societies just don't have this much wealth, and if they do, it tends to be highly concentrated in the hands of a few individuals. In short, you need a pretty well-off middle class. Also, authoritarian and communistic regimes are unlikely to view the media as a vehicle for selling products, hence see no need to allow the media to progress beyond the Elite stage, or only somewhat into the Popular stage, and only then in an instructional mode.
Capitalism is based on the notion of the supremacy of the individual.
The economic system functions because of the law of supply and demand. This means that if there is a market for a product or service, it will be produced. The key is the government role is minimal. Capitalism understands, in the sense that Hobbes did, that people seek their own advantage, and are ultimately driven by what they believe will help them the most. The idea is that this will produce competition, as people seek to make more money, which ultimately is good for consumers.