Measured by LOC, a lot of code in systems i've worked on is just copying data from one type of object to another. One frustrating bug I've dealt with was due to someone copying the wrong value between two similarly-named fields, but the request went through so many layers of the system before it was processed by the buggy code that it took hours to track down.

I've spent a lot of time thinking about how to write less of this code, and I think what I want is something similar to Postgrest, but with a mechanism for some sort of hook, where I can write some code to manipulate the request/data in a type-safe way.

The closest I've seen to this was early in my career - one of my first jobs was working at a WebObjects consultancy. Because WebObjects provided the full stack from HTML templating engine to ORM - and by that time also community-driven frontend libraries - you had to write very little of this type of code.

I suspect also that some of the resistance to the Postgrest-style approach in enterprise environments comes from tighter controls around data, and requirements/expectations for stricter change control around databases. Buggy code can always be rolled back, but a botched database change could be a much bigger problem. (Of course, the fact that buggy code could corrupt or delete data almost as easily is ignored in this calculation). I still remember weeks of meetings at one employer trying to get a column added with the ultimate answer being 'no'.