Interesting. I think I find it more natural to look to the right, but I think if I was faced with five people at a bar, and no idea who came first, it would feel most natural to serve them in order starting from my left, since I read from left to right. Though of course the chaotic comings and goings of a bar would mean that it wasn't as simple as that.

I'm now thinking about bus stops. If there's a bus stop with one person standing at it, does the queue tend to form to the left or right of that person?