People are sneaky, underhanded liars. Not all people, mind you, but some of the ones I have to work with these days. When I ask you, “have you vetted the changes with so-and-so?” and you say, “yes,” I believe you. Shame on me, apparently, because I should have checked into the details and discovered that what you were telling me and what you were wanting to do were worlds apart. So now it makes me look bad that I gave you the go-ahead but, worse, it makes you look deceitful. Not telling me the whole story is just as bad as lying and will only end badly for you when the lie is discovered.
If I can’t trust people to be upfront and honest without me having to verify every time, nothing would ever get done. But now that my trust has been broken, you better believe I’m going to scrutinize the hell out of everything I’m told. Which is perfect because I don’t already have enough to do.