Working backwards, one of the strongest examples of the hierarchy embedded within social structures would be in the leper colony. Fuser rebels against this structure in which the leper patients are in one domain of the colony and the nurses and doctors live in another cabin. The river that he swims across is the physical representation of this hierarchy, something that Fuser rejects at the end of the film. Such an action shows a repudiation of the hierarchical distinction that is present in the social conditions featured in the Latin America of the film.
Those who believe in Communism are shown to be socially maligned, forced to inhabit the lower rung of a hierarchy because of their beliefs. This is a reality that becomes evident when Fuser and Alberto meet the Communist couple. Fuser's anger is aroused even more when he sees the mistreatment of workers at the copper mine. The condition that angers Fuser is one in which workers and those who advocate different ideas are placed at the bottom of a social hierarchy. Fuser becomes aware that this condition exists in society, a hierarchical structuring in which those at the top of this pyramid experience the very best society has to offer. This is a far cry from those who are on the bottom of it.
Interestingly enough, Fuser and Alberto live the life of those who are on the higher end of this structure. Both of them live lives of relative wealth and power. Fuser is finishing his medical societies, while Alberto is a biochemist. Their lives at the higher end of this social spectrum, a hierarchical configuration in which those who are wealthy can afford to send their children to school for advanced studies. The exposure to the dire conditions of poverty on their road trip is what opens their eyes to the reality of social oppression. While both boys have benefited from their placement on this spectrum, their experiences at the end of the film have shown a rejection of such a hierarchical structure.