All Google code is stored in one master repository, for all products. An intern can look at the search code.
Not so. Search is specifically sequestered.
If you don't trust your employees why did you hire them? Besides, the source code isn't where FB's money is at, that would be their users.
> If you don't trust your employees why did you hire them?
On a small company, I agree. But on FB they're around 5k people. Let's say they have 3k engineers, that's a awful lot of people they're trusting with their source code
Google is also one source tree I think.
You are correct for the search codebase - it is separate from the main tree, as is a lot of the core ad placement code. If you aren't working on those projects, you don't have access.
I doubt that an intern on Google would've access to the search codebase. I'd wager that only a handful of trusted employees have access to that codebase.