To answer this question we should go to each country and analyze its particular revolutionary situation. In regional terms one of the macro explanations is the national security doctrine that led the armed forces of the respective countries to act as a counter-revolutionary force and install anti-Marxist dictatorships (this is true at least for Argentina, Chile, Brazil, Uruguay). This doctrine saw the revolutionary groups as a threat to the nation, which geopolitically was the backyard of the United States and there was a sort of silent cold war treaty where the zones of influence of the great powers would not be intervened by the enemy. The national security doctrine was taught by the United States to Latin American armed forces personnel in the infamous school of the Americas, and this included among the theoretical questions of the dangers of revolutionary groups, techniques of torture to confront the threat. In other words, we could say that Latin American countries had antibodies against the revolution (without even questioning the very effectiveness of the revolutionary groups).

Usually the Cuban revolution is seen as a transcendent milestone, meaning that the revolution was possible in Latin America, this corresponds to a heterodoxy of the classic Marxist theory where the revolution happened in countries with a certain industrial development. Although it was seen as an expansion of the socialist camp and the USSR, the revolutionary process was more similar to Mao than to Lenin (the only theoretical overcoming of "Che" Guevara would not needing the party as a necessity for the revolution). Moreover, after the Cuban revolution the USSR was unable to maintain the same treatment with other emerging socialist states (sugar for oil). Specifically, what happened in Cuba can be explained by the low legitimacy of Batista's state, which supported by the United States, was part of the post-colonial revolutionary process where the peasantry saw with good eyes the challenge to Batista (note that Fidel did not declare himself a communist before the revolution, it was a geopolitical move to assert his power).

In the case of Nicaragua, the social forces that influenced were the church (liberation theology) and the revolutionary groups. Now here we are talking about a revolution that happens 20 years later with characteristics of formal warfare and not guerrilla warfare with strong Cuban support in the process. But we could say that the situation of lack of legitimacy of the state in both cases was similar. While in the rest of Latin America the state administered the respective crises resulting generally in right-wing dictatorships.