[alasdair_]

Your example of “Looks like we have the wrong order. We ordered X” seems perfectly polite to me.

You seem to have the opinion that basic politeness is manipulation. I suppose it can be construed as such but only in the sense that all communication is manipulation in some sense.

[ChrisMarshallNY]

Here's one way to learn courtesy:

Deal with folks that are on the bad end of the stick, and consider violence to be an appropriate way to solve problems. Be someone that is trying to help them, which includes teaching them that there are other ways to resolve issues.

This kind of relationship means that we need to have an empathetic, respectful, authoritative aspect, but that we also need to realize that we could have a real, physical threat of violence directed our way, if we are not respectful and courteous (and sometimes, even then). We also need to not be doormats.

Teaches you to be polite, but firm, real quick.