1) avoid the personnel costs associated with training a human to answer the telephone and actually address the customer’s problems. This is caused by the belief (often true) that the caller really doesn’t know what they want, and needs to be “sorted”. The fact that a human caller speaking to a human directly will assume some level of competence and intelligence is negated by having a machine do the work.

2) avoid having a person actually required by the duties of their job in answering those telephones to hold their temper and be pleasant to an endless parade of idiocy and impatience.

3) appear to be providing a service, while in fact providing a disservice to the callers.

4) potentially avoid any and all human contact with the caller, as humans are not “binary” in their responses.

5) feed programmer’s egos by allowing them an opportunity to design something impossible, reducing all business interactions to the binary game of “Twenty Questions”.