Well Android does have a Linux kernel. The permissions happen at different layers within Android, as apps are run on their VM (Dalvik byte code). The /system partition is read-only on Android, but I don't /think/ you'd need any special permissions to read most of the system partition. The data partition is what's protected.

I mean, an application has to be able to read standard libraries to function, right? Same with any traditional Linux distro and /lib, /usr/lib. Really tight Apparmor or SELinux profiles can lock this down a bit.