lol you guys are being too nice. Building CRUD apps is just implementing business logic by gluing APIs together, there is nothing to understand except the business domain, which is only done through exposure, because business logic is random. And then the APIs which are all essentially a kludge because of the shifting business logic.
Understanding low level code puts you on entirely different level because you can reason about a problem using logic and how systems operate.
No disrespect to any crud devs here but from my personal experience they just know a particular implementation of their domain and rarely even consider how the code base even operates as a whole