I remember the movie “Internal Affairs” where Andy Garcia is being introduced into Internal Affairs as the new detective. The superintendent, basically a political hack, welcomes him with a speech about how the rumours about the hatred of cops investigating cops is overblown, how important the work is, how it is a necessary check on police misdeeds, and that this unit has the support and respect of the entire force - that they recognize his role in making the force more accountable and therefore better, an initiative all police believe in. The super leaves and Garcia’s unit sargeant, who stood by quietly while the speech was going on, shakes Garcia’s hand and says “Welcome to IA, you’ve just lost every friend you ever had in the LAPD”. The Blue Wall absolutely exists. Like Noah said, individuals can’t or won’t speak up against the system.