I suppose I could give them the benefit of the doubt and assume that when they're expressionless, they are experiencing no emotions.

It's obviously true that not everyone has a desire to be authentic. That fact need have no effect on me. It's not like I can force everyone else to be authentic. It makes more sense to accept the world as it is, (complete with expressionless people) than it does to demand that everyone act like I want them to act.