The systemd service manager does not have an installer, systemd-sysinstall is a separate tool that's part of the systemd project.
> systemd already integrated it, why (age verification)
systemd has not integrated age verification. All that's been discussed is a simple field to allow a user to register a DoB and an way for services to validate the user is over a certain age.
You could arguably already do this by having a DoB field for the user, but that'd involve giving applications your full DoB which I'm sure is distasteful for many.
> usual "fight" against non-sense laws
Because developers have to follow laws like everyone else?