What is the author’s purpose for including this sentence? "Shallow understanding from people of good will is more frustrating than absolute misunderstanding from people of ill will."

Because people believe being helpful for the wrong reasons can be more cruel hen just being plain unhelpful, as an example. As an example, if you are in a job only for the money, you won’t do as great a job as someone who is in it for the cause

By by showing how hard it was for the sisters to feign grief