While, on its face, it seems like a good idea to discourage lying, presenting children with such a binary approach to deception might leave them underprepared for the "bullshit" (marketing, propaganda, etc...) they will encounter in the real world.

EDIT: I'm not a parent and don't want to offer parenting advice. My point is simply that saying "we never lie" seems overly-reductive, versus something more nuanced like "lying is bad." I would worry about creating the expectation that most people don't lie, or even that good people never lie (e.g. white lies).