You probably have never seen this happen, hence your naiveté. When a bunch of cops show up at your door, each of them doesn't identify themselves separately as

You probably have never seen this happen, hence your naiveté. When a bunch of cops show up at your door, each of them doesn't identify themselves separately as a cop. The leader will usually announce, "SFPD! We are here to investigate blah blah blah...", and probably show a badge. His other comrades will just stand there. They don't go down the conga line, each swearing an oath that they are cops. It is assumed that the first announcement is enough to establish authority.