Avinash Kishore tells you why people do not use surnames (that indicate caste) in a ‘place like Bihar where caste-identities are so strong’:

Now, it is neither the inspiration to create a casteless society nor the fear of caste discrimination that motivates people not to give their family names to their kids. It is just the convention in Bihar and to do otherwise is to be old-fashioned, traditional or even reactionary. In and of itself, I think using or not using family names does not make any real difference to people’s lives. It is not even a real issue but it tells us something about Bihar’s post-independce politics where something starting as a lofty gesture towards undoing the problem of casteism eventually became (an ineffective) coping mechanism as the problem worsened and society remained unprepared and unwilling to take any meaningful action.