I love the folks at backblaze but the single datacenter thing really worries me (and again, disclosure, I work on Google Cloud). If you're just using it as another backup, maybe that's less of a concern: your house would have to burn down at the same time that they have a catastrophic failure. But it is part of the reason you see S3 and GCS costing more (plus the massive amount of I/O you can do to either S3 or GCS; I'd be curious what happens when there's a run on the Backblaze DC).
Sorry if I wasn't clear: your bytes on GCS and S3 are stored across multiple buildings (GCS Regional, S3 Standard). More copies is more dollars not less ;).
As far as I am aware GCS does erasure coding across sites?
Backblaze could do multiple tiers of erasure coding and they would still be able to reduce prices given more scale, ceteris paribus.
It's not a question of number of replicas, data centers or technical implementation, but a question of pricing policy.
Does one want to use volume and scale to drive prices down (and cheaper prices to increase volume) or does one want to use volume and scale to bloat margins? Backblaze are arguably doing the former.
Does one want to lock customers into an ecosystem by enforcing excessive bandwidth prices or does one want to pass on bandwidth cost-savings to customers? Backblaze are arguably doing the latter.
Backblaze would continue to be cheaper because their pricing policy serves customers across all dimensions.
More scale is definitely less dollars not more (even if it means a fraction of a few more erasure coded shards across sites).
Again, huge disclosure: I work on Google Cloud.