IME, Swift's access control* is such a delight to use that the old type-based system feels ancient no matter what languages I switched to. I can't quite put it into words, but Becca's word strongly resonate with me:
* No, not you private. You're stealing fileprivate's place again... 
Digression aside, I'm not sure I ever have a problem with one part of the project accessing other parts because of them being internal. I do get somewhat paranoid in the beginning, but nothing ever comes out of it, even as the projects grow in size.
Though all these talks about security and trust make me think I might be missing out on some fun people are having. I mean, access control is such an easy thing to bypass that they're usually more about convenience than concerns.