Your “plain language” goes from “do a thing” very quickly to “do a thing. but not that thing. or that other thing. and and and…”

Your options would be write all those things in plain language, or program them all eith (hopefully) no mistakes, bugs, or vulnerabilities. Either way you have to catch all the situations. Even in plain language, not everybody will be able to effectively use AI to generate code. You need to have a solid understanding of software architecture to be able to get useful output.

when it comes to creating programs, you want the output to be deterministic

AI is capable of writing deterministic programs.

I would also like to preemptively emphasize that AI is not there yet. I am simply talking about the concept of machines creating software. If you try to step back from your anti-AI gut reaction and truly think about it, it would make sense to do if we get there technologically