I like the traffic lights example, because it demonstrates civil obedience; cooperation with their fellows in society, in general, regardless of their relationship, or agreement on ideology or religion.

I agree on in-group/out-group (and, eg, monomanical movie villains, abusing their blindly obedient minions, are unrealistic). I'm claiming the benefits of civil cooperation are so enormous that these in/out-group clashes will occur on an increasingly higher base of mutually beneficial cooperation. Because an in-group too separated is too weak.