The cops, on occasion, do get the guy, maybe a small time crook, or someone caught red handed, like Ian MacAllister, or Dr. Baker. But I do agree that the writers just have the cops/detectives spin their wheels when it comes to bigger crooks.
Amazing no one ever saw Jeremiah, despite his unusual looks. Or have looked into the takeover of the trucking business more closely. Don't you wonder if they are still investigating the death of EJ, or stabbing of Sonny.
And then there is the oh so religious ex-priest, Eric, who was so holy, so religious, so judgmental of Nicole shredding papers, who knows all about the smuggling of diamonds by Xander & Serena, but has not said a word to any authorities, not even anonymously giving a tip.