Obviously, in this case, it was just one interaction in a string of interactions and there's no real way a random high school girl could do anything to meaningfully help an unrelated adult working at a black company, so maybe it was more about helping the OL feel good about herself despite the sleep deprivation.
That's a pretty cynical world view. Obviously this isn't true for everyone, but some people just need a little encouragement or a boost in confidence, even a small one, to improve their outlook. That kind of thing can be life-changing. Do something nice for somebody you don't know when the opportunity arises. You'll feel better, and you might even save someone's life.