Re: Rotten apple
Android apps are also properly sandboxes, u less you grant the write external storage permission. However Android also has a browsable filesystem. You can't browse applications sandboxes, but you can open up a file explorer app and browse downloads folder, browse all your music stored on your SD card etc etc..
Its the perfect half way house, where application data is sandboxed and private by default for most types of apps, it with a permission based extension to make things work like a real device for more complex or open storage requirements.