Former employee and it's been a few years, but for what it's worth I was actually very reassured by what I saw there in terms of internal data security. For all products I worked with or knew something about in an engineering capacity, there was no unlogged access to personal data. Access to personal data without clear, approved reasons would result in termination. The controls were extremely strong.

I'd be more concerned in Google's case about "legitimate" but still problematic uses of data: disclosure to law enforcement, crazy specific ad targeting, machine learning for military applications, etc.