I get a lot of mileage out of GPT, so let me see if I can explain. I wouldn't ask GPT/Copilot to do what you asked. After using them for a while you start to get an intuitive sense of what's easy and what's hard for them to do, and your specific example is indeed too difficult to get GPT to do properly. They have the biggest utility for me for stuff that I would ask a junior programmer to do - like a new grad.

The real value proposition of GPT isn't that it can solve really hard problems. The value proposition is that it's about as capable as a junior engineer, except it can write code much faster than any junior engineer, so it can speed you along on the boilerplate-y parts of coding that otherwise would be a lot of manual effort. It's especially useful for things that feel "easy" but which I don't have the relevant domain expertise. For instance, the other day I needed to write a fairly trivial shell script to parse some JSON files. I never write shell scripts and I always forget the syntax, but GPT wrote it correctly on the first try. That probably saved me 20-30 minutes of googling for how to do things like read files, etc in shell scripts.