I assume every phone is a different user, and she just goes around rating apps. I am not sure if you could automate that process, but then why would the phones be arrenged in such a way that one person can quickly click on every one of them, instead of a dark room.
Probably could automate it, maybe even by using a Mac and multiple instances of the iOS simulator, but that would require a lot of expensive development, so it's likelt much cheaper to buy a bunch of devices and hire super cheap labor.
You could build a hardware rig that's programmed to hit the 5-star rating area, and then "submit" - but you'd also need to find a way to launch the app store to the correct app every time, and then debug the thing, and then still pay someone to stand around and watch in case it gets into trouble anyway.
Open CV could easily help in that area. Servo controlled stylus for input, OpenCV based watchdog against pre-programmed motions. Maybe mechanical turk or something to generate the reviews.
Perhaps you could fight it by doing statistical analysis on review patterns. If the device is only ever giving great and/or crappy ratings and the same group of devices rates the same group of apps the same way, you could detect this.
Edit: Of course, they could fight detection by having a queue of apps to review and an array of devices. Randomize the matrix and periodically retire a device to prevent it from gaining too much history. Since it's running in a machine it would likely be in pristine condition and capable of being resold as new. Heck, they could buy one, use it for a period of time then return it.
