I always confirm the day of just to make sure her plans havent changed.
The girl in the post should have just confirmed if the dude didnt. She probably doesnt want to look like she is doing the chasing but that is stupid to me. We dont know each other, so you are dealing with 2 different communication styles.
At a certain point, an adult needs to be an adult. Hell, I confirm plans with friends on the day of our gathering.