http://www.twincities.com/technology/ci_22642126/minnesota-cellphone-amber-alert -located-child-and-was
There is your example of it really working. It worked back in February in Minneapolis, just a couple months after it went live. Now, eat your shorts and enjoy. All you conspiracy nuts are funny. This system is going to save a lot of kids and also will alert people to severe weather like tornadoes. It is a one-way system so the government has no clue where you are or what you're doing, so it isn't big brother.
If you don't want the alerts, turn them off. If you're too self-centered to want to know when a child is abducted and you might be able to help, well, then you are just probably not the type of person that needs the alerts. If you have a kid, or have one some day and someone takes them, I think you'd hope everyone gets the alert in the hope that someone sees the car and calls the police.