Or I refuse to cooperate in making Britain a surveillance state because there is no guarantee that we will forever have a benign government.
I'll give you a true story of a maniac with a grudge who overtook me then brake tested me. I had my wits about me and drove around him. No camera required but my eyes.
However bad being brake tested is, there's still no excuse for being caught out by it. Either you were driving too close or could have used the lane to the right the brake tester was previously in to avoid a collision.
But how does this argue against dashcams not reducing insurance premiums ? If the guy is clearly seen from the dashcam as delibrately trying to cause an accident, any right minded person should make the police aware of the attempt. Also should they come across someone without your wits, the insurance campany will use the video to deny their claim if it is clearly shown that they acted to deliberately cause an accident. "A rabbit ran out in front of the car", doesn't really work when there is video that shows there was no rabbit.
if both scenarios happen often enough, it'll end the insurance scam.