Why does Julia believe that Dr. Lynn is coming into the hospital to help out of the kindness of her heart?

Dr. Lynn tells Julia that she is late arriving at the hospital because she was busy at her own free flu clinic and had not received the telegram. Julia surmises that if Dr. Lynn has her own practice and a free flu clinic, she does not need to work at the hospital to earn an income. She must be doing it to help out a hospital in need.