So who makes the decision to do that?

I think most people are missing the point about accountability and thinks, in typical American fashion, about punishment. Accountability is about being responsible for outcomes. That may mean legally responsible, but I think far more important is the knowledge that "the buck stops with me", someone who is entrusted with a task and knows that it is their job to accomplish that task. Said person may decide to use a computer to accomplish it, but the computer is not responsible for the correct outcome.