I suppose the complexity of the domain is the main driver of the difficulty level. Perhaps that's the intuition that I'm trying to pin down: programming itself, the typing of words for the compiler, the act of converting pure thought into code, seems mechanical at best. But if you include the act of abstraction itself, then I concede it changes the equation. I don't find it to be all that clear what is and isn't programming to be honest.

Especially once you get to describe your abstractions in plain (or slightly technical) English instead of code I find it hard to say "programming" is being performed, but in many ways the case could be made that it remained the same and only the shape of the artifacts is different now.