I think this works well to describe the behavior of small, well-mixed groups, but as you look at larger societies, it gets more complicated because of the structure of social networks. You don’t get to see how many people overall are wearing face-masks in the whole country, only among the people you interact with in your life. So it’s totally possible that different equilibria will be reached in different locations/socio-economic classes/communities. That’s probably one reason why revolutions are more likely to fizzle out than it looks. Another problem arising from the structure of social networks is that the sample of people your interact with is not representative of your real surroundings: people with tons of friends are over-represented among your friends (I had a blog post about this statistical phenomenon a while ago). I’m not sure how one could expand the social behavior curve model to account for that, but it would be interesting.