> and why that’s a particularly difficult problem to solve

The person I responded to, who seems like someone who definitely knows his stuff, made a comment that implied it was a technically difficult thing to do, not a trivially easy thing that's completely explained by "welp, $$$", which is why I asked. Your comments may point to why ChatGPT doesn't do it, but they're not really answering the actual question, in context.

Especially where the original idea (not mine) was a lightweight LLM that can answer basic things, but knows when it doesn't know the answer and can go ask a heftier model for back-up.

I think that person should think that technically difficult thing that makes more money = gets solved and technically difficult thing that makes less money = doesn't get solved.

By the way model's don't "know". They autocomplete tokens.

> Your comments may point to why ChatGPT doesn't do it

Any commercial model which is most of them...