In junior high it's called a fear of being different.
In our Christian journey and faith walk it's called being human.
In psychology it's called the bystander effect. Everyone sees what's going on, everyone knows someone needs to step in and help, no one does. Everyone naturally assumes someone else will do something and so we all stand by, our feet stuck in cement.
There are many reasons why, when in groups, bystanders don’t act in emergency situations, but social psychologists tend towards two major causes. Mark Levine and Kirstien Thompson write in the “Journal of Social Psychology”, “according to a basic principle of social influence, bystanders monitor the reactions of other people in an emergency situation to see if others think that it is necessary to intervene. Since everyone is doing exactly the same thing (nothing), they all conclude from the inaction of others that help is not needed. The other major obstacle to intervention is known as diffusion of responsibility. This occurs when observers all assume that someone else is going to intervene and so each individual feels less responsible and refrains from doing anything.”
I get the sense that Joseph and Nicodemus were poised and ready to defend Jesus at his trial. All they needed was someone else to defend him first and they would have been the first to shout back a roaring, "Hear, hear!"
We can freely admit to moments when we have failed to announce we are on Jesus' side. Each of us has stood by and let opportunities to proclaim our faith to pass. But what about those moments we've had to proclaim justice, equality and responsibility to the least and the lost? Can we say we've done what we could to step in and help others? Or are we standing by, waiting for someone else to speak, fully prepared to shout, "Hear, hear!"