I see your point. I don't think it's different in kind, just degree. My thought process: First, is my dad's accountant infallible?

If not, then they must themselves make mistakes or do things suboptimally sometimes. Whose responsibility is that - my dad, or my dad's accountant?

If it is my dad, does that then mean my dad has an obligation to review and fully understand everything the accountant has written?

And do we have to generalize that responsibility to everything and everyone my dad has to hand off work to in order to get something done? Clearly not, that's absurd. So where do we draw the line? You draw it in the same place I do for right now, but I don't see why we expect that line to be static.