Just this morning I stopped at McDonald's for breakfast. I gave my order, they entered it, and it showed up correctly on the screen at the drive through. However, the order taker read back something completely different (than what they just entered). Since I saw that the order in the system was correct I ignored that and simply said "sure that's right."
This is why I prefer an interface that bypasses the human order taker. They may say one thing and do another. Even in my case, they may have then thought "well he confirmed what I just said back, and that doesn't match what the screen shows, so I'll fix it to match what the customer agreed to." Then I would have the wrong order. That can't happen if I interact directly with the order system.