I make a living selling working code, but I agree. I think that, just like how monitoring needs to run at higher priority than actual production workloads, the understanding of programmers needs to be at a higher level than the understanding which is actually encoded in the actual production program.
I agree as well, and the real test of understanding comes if I forget to create a backup and lose my program.
Rewriting the same thing from memory when I already know how to structure the program is boring but fast.
Professional software engineers develop and sell solutions. Code by itself is meaningless, it's the application of code in certain parameters and delivering expected results, which results in solutions.
There's no such thing as a working system.
That's why space stuff has redundancies etc.
one can argue that redundancies is part of a working system, in fact most large distributed systems are designed with redundancies.