Maybe they consider this report to be an ad for their services? The name recognition this report gives them is probably quite valuable.

To quote them : Transparency breeds trust. We’re in the business of asking customers to trust us with their data. It seems reasonable to demonstrate why we’re worthy of your trust.

I’m sure Amazon, Google, Facebook, etc collect their own stats on drive failure. It would be almost negligent if they were just guessing in the dark every time they buy drives.

Main difference is probably Backblaze is small enough to publish these stats without hurting their supplier relationships. (pure speculation)