It's one of those things that we script in to make it feel more comfortable for humans - add in those little things that we're used to.

I'm reminded of a national tour put on by Nissan for the All-Electric LEAF when it first came out. We were told by our presenter that there was an aluminum cover under the hood designed to look like an engine block - apparently it was discomforting to people to open the hood and not see that component.