Capitalism has been attributed to Gamma for being associated with the ability to accumulate money, power and wealth. But if you take another look, Capitalism is actually an Alpha/Beta economic system as it is fundamentally an expectation-conform economy.
In Capitalism, the state of the economy is presented to officials and holders of capital and they analyze the status and conform to the expectations. The means of production and output are largely controlled by implicit factors.
Communism/Socialism is a command-execute economic system and therefore Gamma/Delta. The means of production and output are controlled by explicit commands from the ruling party, whether or not these commands were necessitated by nature. Thus the economic actions are efficient as production only executes what it needs(or, more accurately, what the government says it needs).
So, the question is, why is Capitalism so heavily associated with Gamma? Maybe because Gamma can observe the trends of the economy and capitalize on them to acquire objects of value, but Gamma still perceives the highly inefficient economic system of a democratic capitalist state.