Mold free construction is quite easy, especially in our dry climate. The key is breathability.
In my restoration work, I deal with a lot of mold. It is always the result of a combination of moisture ingress and vapor tight construction practices. This keeps the materials wet so that mold can digest them. Remediation generally entails; removal of vapor barriers and fungal fruiting bodies(sometimes can be quite large), then clean up with vinegar solution and re-sealing the wall cavity with breathable materials like lime plaster. No vapor barrier is needed.