Comment by retrovm

It seems like there is an inverse relationship between sophistication and risk. If everything is full-custom then it may be quite easy to integrate auditing tools for who accessed user data. If an org uses mostly off-the-shelf software then it's pretty much impossible to audit e.g. who connected to what mysql server and ran which queries. So I'd be a lot more worried about a Twitter (fairly unsophisticated deployments of standard software stacks), moderately worried about Facebook (hacks upon the usual stack) and not very worried about Google (literally everything written in-house).