Actual experts disagree. For example Ekman, for the basic emotions at least (see the link I posted above). To quote:

In the late sixties, Izard and Ekman in separate studies each showed photographs from Tomkins’ own collection, to people in various literate cultures, Western and Non-Western. They found strong cross-cultural agreement in the labeling of those expressions. Ekman closed the loophole that observing mass media might account for cross cultural agreement by studying people in a Stone Age culture in New Guinea who had seen few if any outsiders and no media portrayals of emotion. These preliterate people also recognized the same emotions when shown the Darwin-Tomkins set. The capacity for humans in radically different cultures to label facial expressions with terms from a list of emotion terms has replicated nearly 200 hundred times.[1]

The FACS coding system[2] has pretty good experimental support, across multiple cultures. As noted on this article, it can distinguish between fake smiles and real smiles etc. See https://en.wikipedia.org/wiki/Smile#Duchenne_smile for more on this.

Even if you disagree with that and think that motion is required (which is an argument that has some validity) there is still no reason to think a computer system can't do it.

[1] https://www.paulekman.com/blog/darwins-claim-universals-faci...

[2] https://en.wikipedia.org/wiki/Facial_Action_Coding_System