It provides your deployment team with:

Confidence that only definitively-authorised container images will be deployed to Kubernetes

A reduced risk of any inadvertent or malicious code being used in your environment

https://docs.thoughtmachine.net/vault-core/4-6/EN/environment_and_installation/infrastructure_docs/infrastructure_and_installation_guides/using_binary_authorisation_and_docker_images/#binary_authorisation_overview-benefits_of_using_binary_authorisation