The Torah's appeal is to conscience. The individual is both defendant and judge. In this context, the Torah addresses the inner disposition from which action flows. Our instinctive response is not to take the time or trouble to get involved. The prospect of personal gain only compounds our inertia while mortal fear strikes us with complete paralysis.
Morality requires overcoming our baser selves.
The bystander is unpunishable but always compromised. In an early novel, The Town Beyond the Wall , Elie Wiesel gave flesh to the phenomenon. Michael returns to Hungary, to the town of Szerencsevaros, to confront the neighbor from behind his curtains who witnessed the great roundup of Jews in the courtyard of the synagogue without offering so much as a glass of water. When he finally meets his nemesis, Michael unleashes his pent-up indictment. The role of spectator suited you to perfection.