I remember the pre-AI Geico chat bot that I liked. I could call it once every six months and pay my entire balance with a few words. But then the company started leaning harder on monthly payments and the "pay entire balance" option was removed and I now must either laboriously speak-out the entire dollars and cents due or talk to a person.
What is to say that a lot of the functions that a customer service person does is getting people things they need and that the company resists giving to them. Which is to say that companies mostly need customer service agents because the company's raw impulses are so shitty they need someone with the slight independence of a customer service agent just to provide the services their customers need.
It's like why I never go to company websites despite being very web-savy. These websites only serve the company's idea of what I get and if I'm calling at all, it's because I need more than that.
Naturally, the point is an AI chat can't do customer service because it can't override policy, tell people tricks and similar things.