You say > We have had this kind of technology for years. and > For these simple use case, I still think a binary algorithm would be, on average, more efficie

You say > We have had this kind of technology for years. and > For these simple use case, I still think a binary algorithm would be, on average, more efficient for both the caller and the business. The fact that we have had this technology for years, and nobody has been able to make it work as you describe, suggests that it's not as simple as you think. My take: sometimes you can persuade users to learn a new UI, but consider the stereotypical grandparent that still can barely use email; teaching a new UI is hard, normal non-tech people don't like it, and it will take more than a generation to reach 100% penetration. The existing UI of using a telephone and conversing like a human is probably not at 100% penetration either (e.g. considering deaf individuals), but I'd wager it's as close as any one UI is going to get.