To provide a non-Google example, AWS DynamoDB's pricing is based on throughput (similar to Google Cloud Datastore).
One technicality: DynamoDB's pricing is based on throughput, as you know, but it's provisioned throughput. (You manage your capacity unit allocations yourself, at least that was the case a little while ago.) You're charged money for how much you provision regardless of whether or not you actually consume the capacity units. Our pricing model (like Fauna's) only takes ops and storage into consideration.
You'll probably find there are a lot of distributed database geeks at Google, me included, so we all get attracted to exciting posts on new distributed systems.