Welcome, Maatsetungi. Hope to see many thoughtful posts from you.

To give you a courteous answer (unlike the answer above):

Police in America encourage civilians to report crimes and criminals because those reports help them to get bad guys off the streets. For example: Last weekend, 66 people were shot in Chicago, and the Chief of Police went on TV asking people who witnessed the shootings to come forward.

The Mafia and other organized crime gangs are supposed to have a "code of honor" that outlaws snitching and threatens death to snitches. Yeah, sure. The reality is that today, almost anyone in organized crime who's charged by police with a major felony will rat out his fellow gang members if it means he will get a reduced sentence. If you are a "civilian" and you snitch on an organized crime member, you could be in very big trouble because the OC guy may try to kill you to prevent you from testifying against him.