Hollywood is smack in the middle of one of the most notorious sheriff's departments in the United States [1][2] with lots of ongoing prosecutions and a history of federal convictions. They know exactly how bad the police are and show a idealized version in media that's very fictional.
If the writers introduced the so-called good guys as the Grim Reapers or Compton Executioners [3], the viewers wouldn't believe it.
I should have "not nearly as fictional". I know some of it's true, some of it's 'ripped from the headlines', some is rumor, but nothing Hollywood does is ever entirely accurate. Even the documentaries (maybe especially the documentaries)