Well said, Dan.

And for those who are in public service, I'll observe that it also works the other way. Having spent most of my long career as a public servant (and although I now work in the private, for profit healthcare sector, I still think of myself as a public servant) dealing with the public with respect, not taking stuff personally - anytime (and there have been many) when a citizen/customer started out an encounter taking out their frustrations on me, it is not a difficult task to understand the attack is not actually personal, but directed toward what my position represents, even if the the attacker doesn't recognize that themselves. From that place, it is usually relatively easy to convey empathy and not to react to surliness with surliness.

It helps if the public servant understands they are a public servant and so do not lead the interaction with surliness to begin with.

I will say that I am a bit of stickler regarding service. I expect good service and I expect to give good service. It is possible to not tolerate rudeness from anyone without being rude oneself by being calm and assertive and making respectfully clear one's reasonable expectations to be dealt with respectfully.