Turn signaling

It is one of my greatest pet peeves when people don't signal before they turn.  I'm of the opinion that lack of turn signaling causes more accidents than other things that people get tickets for: namely not using seat belts.  Sure. I understand that seat belts save lives when accidents occur, but isn't it equally, or perhaps even more important to prevent accidents from occurring in the first place?  I wish the police would crack down on people who don't use turn signals more.  

When I ride with people who don't use their turn signals and ask them about it, they say it annoys them or they're just too lazy to do it.  Please allow yourself to be annoyed 5 seconds at a time when changing your lanes in the future to possibly save lives...