And how many photographers behind the camera expect these stiff poses as well?

I used to work as a costumed interpreter in a museum (1860s) and have had thousands of pictures taken of me over the course of my work there. If people were polite enough to ask permission to photograph me, I'd usually ask if they wanted me to pose, or for me to go back to what I was doing. Virtually every one wanted a posed shot -- so even as photographers (of the tourist kind), their expectation was of the ultra-posed candid. I did my best not to smile though, to be as historically accurate as possible.