In Williams's short story, the parents don't do anything about the force the doctor uses because they believe the doctor's diagnosis is the key to figuring out why their child is ill. The parents say this to the doctor:
She's had a fever for three days, began the father and we don't know what it comes from. My wife has given her things, you know, like people do, but it don't do no good. And there's been a lot of sickness around. So we tho't you'd better look her over and tell us what is the matter.
The parents want to find out "what is the matter" with their child. In order to get a throat culture and rule out what it might not be, the doctor has to examine the child. It is with this in mind that they stand by and allow the doctor to use the amount of force that he does. They believe that the use of force is to find out how to help the child. In this instance, they believe that the doctor's use of force might be an example of cruelty in order to generate kindness. It is out of their own fear for their daughter's health and the unknown reason as to why she is sick combined with the belief that the doctor is a "good man" who can help their child that the parents allow the doctor to use the amount of force that he does.