This matches my experience with deployments on AWS and Azure. Both are managed db instances, but Azure's is consistently more expensive for comparable offerings on AWS or GCP.
In my experience, GCP Cloud SQL for Postgres has been more expensive than MS Azure SQL. In our tests, CloudSQL also was not comparable to the resiliency offered by Azure SQL. Things like Automated DR and automated failover etc. were not at par with what Azure offered. Not to mention , Column level encryption is standard for Azure SQL.
We pay in total something around 600 bucks to manage around 250 databases in MSSQL servers (with failover for prod databases, DTU based model)
We pay for log analytics more then we pay for Sql Servers.
Those Elastic Pools is a blocker for us on the way to migrate to Postgres from MSSQL...