The facial communication is only necessary because we're negotiating as two people who want to go where the other one is. When it comes to bots they can be forever deferential and always yield to humans.
I understand yea - when it comes to a robot and a human though the human doesn't need to yield. It'll probably take some time to train it into people but humans should always have the right of way.
When people do that it's because both are yielding. They just don't know where to yield.