Though book authors and publishers are listing books in the goodreads giveaway for getting reviews on the website and elsewhere, it is observed that very few goodreads giveaway winners from India are leaving any kind of review on the website
For example Notion press had listed twenty copies of a few book for a giveaway and most of the copies are delivered to the address of the giveaway winner. For most of these giveaways there were about 150 entries. However for many of these books only 3-5 reviews are published on goodreads indicating that the books are either unread, or the winners are too lazy to leave a review of a few words.
If goodreads has a system of rewarding those who leave reviews, the authors will get more reviews for their giveaways especially in India. Some authors are having their own list of honest reviewers, and sending a copy of their new book directly as they are assured of getting a review.