Let me start with some background (for non south folks). Most people in south (Tamilnadu, Kerala and most parts of Karnataka) have only one name - what their parents give them. By some old tradition/culture they also have initials (which happens to be typically the first letter of their father's name). Initials as its name indicates come in front of the name like P.Chidambaram (our esteemed home minister where P stands for Palaniappan our PC's father's name). Mind it - Chidambaram is his name (only name, given name, first name.. blah..).
Our passport folks did not like this, they insisted on last name and that initials should be expanded (disallowed initials). I'm sure it resulted in lots of confusion etc, but mostly people settled on using their father's name (first name) as their last name (since initials expanded amounted to their father's name). This results in some funny incidents when formal settings in west when people are addressed by their last name (which will be your father's name). But mind it passports were processed locally and sensitive/understanding to the local culture they always accepted whatever the initial is expanded to. Proofs with first name and initials is fine. Your school leaving certificate (with P. Chidambaram or Chidambaram P) is accepted for your date of birth proof etc.
Then came our income tax folks (PAN card). They also insisted on last name, no initials etc. People just followed what they did as passport (at-least that is what i thought). But then KYC (know your customer) norms came and our NSDL/UTISL which are subsidiaries for maintaining/issuing PAN card started insisting on address proofs, identity proofs strictly.
Now comes the sordid part. They are insisting on your complete last name being present in your proofs. First Name in this proofs is not sufficient (unlike the passport or bank or any other folks who follow KYC norms). Note that it is nowhere documented (not that i know of) that this proofs should have complete last name - only that the proofs are in your name. Now what is your name ? for these folks their first name is their name (last name is their father's first name which is typically an initial), but not according to our TIN folks. Your proofs should mandatory contain the last name. This seems to be a case of taking some rule and applying it blindly without being sensitive to cultural aspects. In most parts of India people have Surname (and NOT last name) which typically identifies their caste/occupation (long back). The rule seems to have been interpreted assuming everyone has such surname.
So how do all this people in these states are getting PAN card (after this rule is enforced). Not sure but based on one of my recent experiences it seems like people have gotten around this issue by making their name (whatever parents gave them) as their Last Name (since it is there in any proofs always) and funnily making their father's name as their First Name. In-fact the out-sourced franchises where you can apply for PAN insist on this. So your parents given name (which is universally the first name/given name) becomes last name and your inherited name (your father's or family's etc) becomes your first name. Confused? So am i.
Think about women's case - whatever her parents given name is becoming her last name and her father's name is becoming her first name. After marriage she might change her family/last name/initial to her husband's. Now according to PAN card she'll have to update her first name (since that changes to her husband's name from father's name) and NOT her last name (which is her only name). Does it make any sense? Not to me.