The author failed to mention which regions these tests were run. GPU availability can vary depending on the regions that were tested for both Cloud providers.
The regions used are "us-east-1" for AWS [1] and "us-central1-b" for GCP [2].
1: https://github.com/piercefreeman/cloud-gpu-reliability/blob/...
2: https://github.com/piercefreeman/cloud-gpu-reliability/blob/...