>>How is that different from handwritten code ?

I think the point he is trying to make is that you can't outsource your thinking to a automated process and also trust it to make the right decisions at the same time.

In places where a number, fraction, or a non binary outcome is involved there is an aspect of growing the code base with time and human knowledge/failure.

You could argue that speed of writing code isn't everything, many times being correct and stable likely is more important. For eg- A banking app, doesn't have be written and shipped fast. But it has to be done right. ECG machines, money, meat space safety automation all come under this.