Are you familiar with the design of the Google systems WRT securing this data? Based on the revelations Snowden was able to do, and a similar level of familiarity with Google's security measures, it sounds like Google even has the NSA beat as far as keeping data secure. In short: Even the people doing OS and hardware level maintenance of the machines in question don't have access to this data.

But I'm on the outside looking in, someone with more hands on can probably provide more details.