. . . all good and logical reasons to avoid honesty.
Unfortunately this inclination to avoid the truth is self-reinforcing. As children we learn that avoiding the truth frequently saves trouble (Did you break that?... Nope).
Fast forward to adulthood.
As we grow up we often fail to notice that we have grown in stature and that we have a voice with more own authority...and we still worry about getting into trouble.
We show leaders and their teams what it's like to adopt honesty as a liberating, quicker way of getting to the solution, of getting difficult things done.
It doesn't take long before people start to talk about things that they had historically avoided. Small examples of openness in the group grow in frequency annd magnitude.