> asking a coding agent “why did you do that” to be illustrating a misunderstanding in the users mind about how the agent works

I think the same thing, but about agents in general. I am not saying that we humans are automata, but most of the time explanation diverges profoundly from motivation, since motivation is what generated our actions, while explanation is the process of observing our actions and giving ourselves, and others around us, plausible mechanics for what generated them.