Yep. At least in my state (Tamilnadu), this is because people gave up caste names voluntarily as part of the anti-caste-discrimination movement, and became mononymous. Then, those of us who had to interact with people and entities that strictly assume a two-name structure started using Father's name as last name, simply because a lot of registration forms (and some people too) cannot cope with the idea that someone doesn't have a lastname.

It's not universal though, or even a majority - a lot of people still are mononymous, and many are confused when Facebook and the ilk ask for "Last name" (and sometimes fill in hilarious things).