To make the reader question what is happening in the story.
Answer: It's better to adopt an animal rather than buying one because animals in adoption centers tend to be more humanely raised while animals that can be bought are usually "produced" by extensive breeding and other inhumane methods. It's more ethically-correct to adopt rather than buy an animal.
A system of racial segregation. It would be like making seperate fountains for the "coloured" or the "white"