This is why Microsoft calls it an Availability Zone, each zone is made up of one or more data centers equipped with entirely independent power, cooling, and networking infrastructure. One zone should not knock out other zones. Zones are also often nearby each other just enough that they have very efficient fiber optic connections between them.

That said, that's how Microsoft handles it, I'm not sure how GCP compares.

It is an interesting conundrum though, what if all your nearby availability zones come down at once due to power loss? I wonder which major cloud provider has the best setup for these sort of events.