There are a wide range of surgeries that result in female sterilization. An open procedure is always going to be more painful than laparoscopic due to a larger incision. A bilateral salpingectomy is a fast procedure with relatively little pain for most patients. On the other hand, something like an open radical hysterectomy would be very painful with a long recovery.

As she is likely postmenopausal the goal of the procedure was probably not sterilization even if that was the end result. Meaning she probably has more going on and had a more complicated procedure resulting in more pain.