There is plenty of provider markup, to be sure. But it is also very much not a given that the hosted version of a database is running software/configs that are equivalent to what you could do yourself. Many hosted databases are extremely different behind the scenes when it comes to durability, monitoring, failover, storage provisioning, compute provisioning, and more. Just because it acts like a connection hanging off a postmaster service running on a server doesn’t mean that’s what your “psql” is connected to on RDS Aurora (or many of the other cloud-Postgres offerings).