How does an Apple device gets recognized as external storage on PC? When I connect any apple device to my PC - it gets recognized as an external storage and I can access all the files (Update:Not all the files - but just pictures) on the device. 

How is this possible? Do all the laptops and desktop motherboards come with an Apple authentication chip and drivers ? 

I am working on a device which needs to read music files from Apple devices - so I am wondering whether I need to apply for MFI program. If the apple devices work as generic USB device without any chip and special drivers, then it serves my purpose.
iPhone will present itself as a digital camera to a USB host so you can use camera software to import photos, such as iPhoto.