A human can read your expressions as you talk. A human can ask follow-up questions. I mean, everybody knows the right and wrong things to say to a border agent too, yet a surprising number of people screw up.
A human is also prone to prejudice and bias, that's why a jury has more than one person.
Hey, I just solved the problem - a whole panel of interviewers with a vote afterwards. And a panel of experts to put together a each panel.
Imagine the job-creation possibilities! Plus, we could probably deport a good portion of CPC supporters!