Invokes the idea that one has to live according to their true values and do what they want. The inauthentic are the ones who deny to live how they want, for instance students smiling in school pictures even though they know school, really, is not a place to smile. However, there are many enemies to this, like practicality, for instance some things basically cannot become jobs, expectations by others, for instance ones that only expect humans to be average, and demands by others, for instance, being FORCED to do something by others. So, in the end, authenticity needs freedom and there is no full freedom in society, thus there is also no full authenticity in society.
In fact, you cannot see authenticity from the outside, the mere sight of another human causes behavioral changes.
Neither can you judge it at all, because your standards of "authenticity" are biased towards yourself.