I've never thought speed cameras did anything other than make roads less safe.

Instinctively, you spot a camera and brake, regardless of whether you're speeding or not. This could cause accidents as the driver behind doesn't see it and hits you as he had no indication there was cause for you to brake.

Stupid money generating accident machines That are useless at preventing what really causes accidents: Careless and reckless driving. But of course, you can't measure someone weaving through traffic on a mobile phone.