Sympathy is felt for Sophy because she is an honorable person in a setting that does not seem to validate individual honor. Sophy is not a bad person. She is constantly being derided by her son, and the fact that she does not retaliate is where one level of sympathy resides. Additionally, Sophy's shortcomings are constantly raised by Randolph, who views her with great contempt. This is another realm in which sympathy is felt. Sympathy is natural when seeing a person contantly being told that their grammar is not correct as they are viewed with scorn and embarrassment
In the end, one has sympathy for Sophy because she does not do what she wants to do. Sophy wants to be with Sam. Yet out of respect for her son, she denies himself. Sam points this out: "Still, you can do as you like, Sophy—Mrs. Twycott...It is not you who are the child, but he." The mother is unable to do what she wants because of fear of her son's reprisals. When Randolph rejects her wishes, Sophy is left alone with the wishes and hopes that were never meant to be: " 'Why mayn't I say to Sam that I'll marry him? Why mayn't I?' she would murmur plaintively to herself when nobody was near." There is much in way of sympathy for someone who shows respect to others and does not receive it in return. This is where Sophy generates the respect from the reader and how Hardy is able to facilitate it.