And not everybody wants to use that option all the time. Asking a human makes you feel dependent more than using a tool does.

Aaaand the logistics of making that call to the company to confirm the amount on the bill can get awkward. IVR and hold-time hell just to get a human to have to explain your predicament as to why you're asking for such a mundane piece of information that was in fifty other touchpoints that you couldn't access as quickly or easily.

(I'm also picturing the poor CSR at the other end of the phone wading through hundreds and hundreds of call logs over the years for simple requests and managers up above screaming 'why is this guy calling us all the damn time costing us money'...)