I know what you should do
Actually, I don't.
I know what I would do in this situation, but I'm not you.
I know what your customer should do, but I'm not her.
I know (and you know, and we all know) what we would do in a given situation, but that's not the same thing.
Empathy requires something extremely difficult: accepting the fact that we are not and never will be in the other person's shoes. There's no rational, universal course because individuals have different goals, different worldviews and different experiences.