Simple answer. Google doesn't cultivate an image of caring about privacy. It's the complete failure of Google PR. It's also due to an outdated notion of confidentiality that kept so much privacy-related deliberations within the company. Google should just publish slightly sanitized versions of their internal PDDs with PWG comments to win back trust. (For people who had never worked at Google: PDD means privacy design doc, like a privacy policy but with a lot more details; PWG means privacy working group, specific teams tasked with ensuring good privacy practices in all products launched by Google.)