Meticulous Clerical records from the Clergy and the Ruling style of Vlad the Impaler

Okay - Parody and mentioning 40K - I'm absolutely going to be referencing the Ecclesiarchy - now for those not familiar - in WH40, there is the Human faction that maintains control via a religious theocracy (there are other elements) - but think the Roman Catholic Church at the height of it's power and influence... Then multiple that by a factor of 10 (or 40...) - and you get the idea.

So - each area has a local Church - which officiates all Marriages, Births and Deaths - and whereas in the WH40K lore - this is a sprawling mess owing to size and it is a parody of the Civil Service with it's inefficiency - we are going the other way - the Clergy, for all their faults are absolutely meticulous in their record keeping.

Consequently the state already 'knows' how many people there are...

Why bother with the head tax then?

Well, one of the most infamous individuals from History is one Vlad Tepes - Aka Vlad Dracul Aka Vlad the Impaler - the man that inspired Count Dracula.

There are many stories about him - but one theme does seem to be very consistent - he was all about honesty and Loyalty. If you were honest, you'd be fine. If not, you'd be brutally tortured and executed usually by impalement (hence the name).

There are stories about him leaving a golden cup in the middle of a village for 24 hours, coming back to it a day later and it still there, paying a merchant for the missing costs of goods, but adding a single extra gold coin to test the Merchants' honesty (the Merchant passed) etc.

Whilst most of these stories are certainly apocryphal - the history books says that Vlad was (even by the cruel standards of the day) quite vicious - but ironically, his brutal method of ruling helped protect Wallachia - and so today he is beloved in Romania. History is complicated.

Anyways.

The Tax is deliberately small - a single coin because it is not about the monetary value, it is about the principle in being honest with your dealings at all times.

Pay the correct amount, or risk being brutally tortured and executed - it reinforces that a small, honest sacrifice is better than the alternative.

I think this gives both an internally consistent answer, plays into the Parody of certain settings and has a few historical (or more likely apocryphal) callbacks.