Developed by Hospitality NZ and built on NEC’s Identity Cloud Platform, the system uses verifiable credentials to allow users to prove they are over 18 for hospitality and event access without disclosing unnecessary personal data.

Or they could have used a piece of cardboard.

https://www.biometricupdate.com/202605/new-zealand-prepares-biometric-age-credential-for-govt-nz-digital-wallet