Introduce ID number at birth or on arrival from overseas

NZ has a range of person registry's. IRD, work & income, health index, student number etc. all work towards the same purpose but they are not merged and not complete.
A national identification number is used by the governments of many countries as a means of tracking their citizens, permanent residents, and temporary residents for the purposes of work, taxation, government benefits, health care, and other governmentally-related functions. NZ should do the same and let the the number appear on an official identity card.