With a few exceptions, using an LLM to perform a useful service is something that almost anyone will be able to do. Therefore these jobs will be not pay well.
That seems kind of like saying "using Excel to add numbers is something that almost anyone will be able to do" -- true, but the difficult part is (obviously a vast simplification) determining which numbers to add, under what conditions, and to decide what to do based on the result.
There is huge variation in how well people can prompt LLMs, prompt-engineering has many tricks that aren't obvious, that's why there's prompt engineers,
