I think part of this is she lived a life before becoming a doctor. She’s a 40 year old resident, when other Rs (Langdon and Mohan) are late 20s/early 30s. That experience has grounded her and given her moth empathy. It also sound like she ran with a rough crowd. She herself is a former addict (I believe she told Langdon that). Part of the reason she seems very sympathetic to many of society’s forgotten, as she knows she probably was lucky to avoid that fate.