This doesn't make sense, because we have systematized the construction of executable programs with extremely high reliability and predictability: we call it "Copy File"

It's the design that is the hard part, and the process of coding is the process of iterating on the design. Even turning the design into an executable is extremely reliable, either running via a VM or scripting engine, or compiling. Those are all very repeatable and reliable.

There are other disciplines that focus on creating and improving designs (like writing, painting, architecture, 3D modeling), but it's not like they're reliable or predictable either, unless you're designing very similar things over and over again. That's true of coding as well, but you don't really end up doing that, because once you've done it 3 times you should make a library and then never do that part again, just the unique bits.

In short, yeah, coding is its own thing, and I doubt it'll ever be predictable unless you're wasting a lot of time and effort doing very similar things over and over.