Well…just using the defaults when creating an RDS Postgres in the console give you an HA cluster with two read replicas, 7 days of backups restorable to any point in time, automatic minor version upgrades, and very easy major upgrades. So unless you start actively unchecking stuff those are not entirely invalid assumptions.
RDS is a great choice, for prototyping and only for production if you know what you're doing when setting it up.
FWIW, this is common in all cloud deployments, people assume that running something "severless" is a magical silver bullet.