I assumed it is $14k/core as for the standard edition it is quoted "Standard - per core". It is a weird for me that in the same table the number above is not per core. Yet you know much better than I do, so I will take your number: $7K/core.
Thank you for sharing so interesting data on the usage. This is very surprising to me, though. At least coming from my background (company providing Postgres Professional Services) we see much bigger deployments usually.
In any case, I expect servers to have replicas for high availability. So even an 8-core server would count for a total of 16 or 24 cores for a 2-3 node cluster, isn't it? And then this multiplied by the number of clusters that you have.
Some of our customers run 1,000+ cores on a single cluster. Or some others which run dozens of clusters, where each cluster is 3 nodes, with nodes in the range of 16 or 32 cores. That all adds to thousand-plus cores and arriving to the 6-7 figures (list price) that I was referring to. It may be surprising to me that in the SQL Server world deployments are significantly smaller. But very useful information!
What I believe is that for sure there's a very interesting use case here. AFAIK Amazon always makes decision based on customer requests and data they have. They have both Postgres and SQL Server on RDS. And if they created Babelfish and published it as a managed service, it's probably because there are a significant number of customer requests. Whether that is licensing savings, license/compliance uncertainty or anything else, I don't know for sure.