It’s highly unlikely that Amazon (or anyone) can reliably find or build datacenter space that is high quality _and_ within a few miles of other such space across all the regions they operate. If they had gone to to such lengths they would clearly state that zones are fully independent from each other. Instead they only say that about regions.[0] So even though I have worked at neither company I’m going to say their concept of a zone is mostly equivalent — independent in terms of power and network domains but in the same building or at most on the same property. This allows them to have the low latency that is touted between zones of a specific region.

[0] https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-re...

Do you have a source of that claim?

AFAIK regions are physically separated, zones are isolated from each other in the same region.