In La Guma's story A Walk in the Night, Michael Adonis lives in what the author describes as "a whirlpool of poverty, petty crime, and violence." Politics and racism are what instigate the downward spiral he goes through in the story, as Michael has just been kicked out of his job in the factory for speaking out when a white boss did not let him go to the bathroom. The boss denied him basic human privileges because the boss is white and Michael is "Colored." In the Cape Town portrayed in the story, "Coloreds" like Michael live under white policemen who despise them. The policemen are described as having "hard, frozen faces as if carved out of pink ice." The story conveys the sense of powerlessness that Coloreds feel in the face of the police and in the face of authority, and the story calls for resistance against them.

The district in which Michael lives is also run over by Americans who leave ships and use the neighborhood as a place to visit whorehouses. The presence of Americans and other foreigners in the district is degrading to the "Coloreds" who live there. The taxi driver in the bar connects the behavior of the whites around him to capitalism and says the "color bar [is] because of the system." Therefore, the story includes a call for resistance to capitalism and to foreigners and blames the capitalist system for the color bar imposed by apartheid. 

Well I think that best answer to this question is to see Alex La Guma writing about his own world (apartheid South Africa)

The fictional character of Michael Adonis nurses a growing anger about the conditions he lives in. Hence, the significance of the ghetto world he travels through. CapeTown, where the story takes place is a 'typical' slum filled with its thugs, gangsters, and prostitutes.

Apartheid South Africa saw two worlds exist side by side: the affluent white and the decayed black worlds that shared so much but was also so different. In the black world we can observe misery and suffering. In short, a conflict between races (political laws and apartheid system) with the overarch message of caring for each other.

Historically, the division written about is similar to the Jim Crow South of the United States pre-1950s Civil Rights Movement. From a literature prospective I would argue a similarity to Dickens "A Tale of Two Cities", though of course Dickens is writing on other issues for a different audience.

When seen within the context of La Guma personal story (he came from a background of left leaning politics as well as sympathy for labour), thus the resistance you ask about is seen in the subtle and not so subtle plots and messages of his books.

Hope this helps.