You're right indeed:) but it depends on what you are comparing it with. In this case the comparison is against other managed cloud storage and databases, and in that context I think the claim holds.

Is it the cheapest possible storage in existence? No, if you take raw disks and put them in a rack, but I also feel it wouldn't be an entirely fair comparison.

S3 is one of the most expensive platforms out there, however. Look at backblaze B2 for an example of just HOW expensive S3 is.

When i moved from S3 to DO, my bill went from hundreds to $20/mo. The only thing that changed was the hosting provider.

B2 is mostly S3-compatible, so if they add the same support for preconditions on writes as S3 and GCS, nothing prevents using it as a backend for GlassDB.