Your point is taken and makes sense. However, what you have to remember is that these women are from the older generation, and they were there in the heart of apartheid, not like the younger generation. In those days, black people depended on the whites to provide them with jobs, and the mentality of these older women may still be there (no disrespect meant there at all). From what I can gather, these women were looking for a job and were told to compete for it (I could be wrong). Also, I'm not entirely sure if they knew what exactly was in what they were told to drink.
Now as a previous comment said, black people in the country may still suffer from an inferiority complex from the 345 years of colonialism and apartheid (maybe it is difficult for you to understand as an outsider, if you are). But these women probably have families that they have to feed, and they 'have no option' but to do what they are told if they want to have a job and be able to stand a fighting chance with their families. This is something that will take us a long time to get rid of, but something I believe we can overcome if enough people work together to fight against things like this.