The very first cop show, Dragnet, was explicitly a PR move to rehab the image of the police in the public's imagination. Every cop show since has been propaganda. Even shows where the police are not necessarily the "good guys", like The Shield or even Chicago PD, normalizes police brutality and the flaunting of basic constitutional laws because those dastardly bad guys have to be stopped at all costs.

I enjoy some of these shows myself but it is sometimes crazy how blatant they are about it.