I’m curious: would you say the absence of a surname implied anything about caste? I’ve dealt with the children of people with leprosy (mostly SC, with a little ST and OBC) in the vicinity of Hyderabad, and it wasn’t dreadfully uncommon for their parents or grandparents to have no surname on their Aadhaar card, at least, and perhaps even a few of the children.

(In Telangana, surnames are almost exclusively used as just an initial preceding the given name, and sometimes that’s even all that ends up on official documentation.)