I'd assume its because, at Google scale, you can dictate what "time" is consider...

		toomuchtodo on Dec 1, 2016 \| parent \| context \| favorite \| on: Making every (leap) second count with our new publ... I'd assume its because, at Google scale, you can dictate what "time" is considered internally. > All Google services, including all APIs, will be synchronized on smeared time, as described above. You’ll also get smeared time for virtual machines on Compute Engine if you follow our recommended settings.