Referees make mistakes during a game the speed of the game and they can't see everything, it happens.
The problem people have is they way New Zealand conduct themselves off the field, when you have time, can review videos, you have plenty of time to exercise good judgement and behave ethically.
It does not happen when you compare suspensions, pulling players off for HIA's, not going to the police straight away when you 'find' a bug in your hotel, (and your coach is an ex cop) no sanction on eye gouging, special treatment from World Rugby to do a dance before their game even when playing away.