Why was Cassie disappointed in Strawberry?

Cassie thought her first trip to Strawberry was going to be exciting, but it was a disappointment all the way around. The town was nothing special outside of the fact it had one paved road and a street light.. Big Ma was then forced to pick up her order at the rear of the market because the white people had priority. Cassie then disobeyed Big Ma by wandering away to look at another shop, and she became angry when the shop owner waited on other "white" customers instead of going in order. When she objected to his actions, the shop owner called her a "nigger."