In my story, when rosa parks writes about her famous bus ride and arrest on december 1, 1955, she mostly uses a chronological text structure because she wants

to explain why she stayed in her bus seat instead of standing.
to compare and contrast the treatment of blacks and whites.
readers to think about the causes of discrimination.
readers to understand what occurred to her that day.

I Parks wants "readers to understand what occurred to her that day." Telling a story in the way that everything happened would be much easier to comprehend then telling a story with a bunch of out of order events. Parks does not want people to be confused about what happened before what. Of course this is just my thought and opinions. I might be wrong so please feel free to correct me in the comments. Have a nice day!