No I don't get the source code for all of Facebook, although they do open source a number of projects, they're widely known or at least suspected of misuse of peoples information and / or meta data and because you can't see the source it's a good reason not to use the platform, and I for one no longer do.
Twitter and google are the same story, they open source many projects and services that run and monitor their platforms, those are trustworthy and it shows an investment in society in general, the bits we can't see however are the parts of I am wary of.
I personally would like to export point-in-time state of contacts before / after sync A) in case anything wrong B) for my own personal trending / information over time