Edit: at least I'm assuming these are the same images as what they run GKE with due to the same name - can anyone confirm this?
[1] - https://cloud.google.com/compute/docs/containers/container_v...
The previous debian based container-vm image only ran upstart.
Debian sysvinit scripts are well understood, are used in production in Fortune 500 companies, and execute much quicker on boot.
Systemd is a mistake, and no one should be backing that project.