Testing is hard. No, sorry, I meant to write that COMPETENT testing is hard. Any idiot can do shallow testing and say he tested, and many do. That's not the same thing as doing a professional job of it.
But, the fact is, AI can't be a software developer, because a software developer is capable of being accountable. AI is a machine. Machines cannot be accountable. You can't sue them. You can't jail them. You can't reform them. A machine cannot be a citizen.
A programmer is someone who mediates the gateway between the world of machines and the world of people. This is because machines behave in very particular ways. Just as you should not represent yourself in a court of law, no one who doesn't understand machines should attempt to create a professional grade products with them... Or if they do, expect it to be poor quality.