systemd added a field where users can add their date of birth. It's completely optional.

It's not implementing age implementation, but can be used as a place to store a DOB in an age verification system.

AFAIK they were implemented by Microsoft staff.

how would it work in the age of everything virtual, from containers to VMs, even an OS instance running in a browser, with OS/kernels being spanned in sub-seconds and existing even for just one call with no user interaction. Are they going to inherit age bracket from supervisor/parent process? Which of course wouldn't work for AWS/GCP, and many other cases. It looks to me like it would require something similar to security labels implementation.