Red light cameras, which are used at busy intersections to catch people running red lights, are being turned off. Aside from some very serious privacy issues, the cameras cause accidents. Intersections with red light cameras are getting 10% to 20% more accidents than before the cameras were installed.
The problem is that once people know the cameras are there, they tend to stomp on the brakes as the light changes, for fear of running the light and getting a ticket. The result is an increase in rear end crashes, as the hapless person behind them (also probably trying to sneak through the light) runs into the brake stomper.
It is a good reminder that technology sometimes creates problems rather than solving them. We always need to look carefully at the promises of vendors before buying new stuff.
On the privacy side, the red light systems have been heavily marketed by private firms that "manage" them system and take a cut of every ticket issued. This is a great pitch to make to cash-strapped government--more tickets, more revenue, and all costs outsourced. But there are some things that should never be delegated to the private sector, and law enforcement is one of them. Getting paid to write tickets invites abuse.