Very true, I will add my stories.
I was driving down Petchaburi Rd when an oncoming motorbike attempting to overtake a bus crossed a solid line onto my side of the road. I swerved to avoid him but he lost control, came off his bike and his bike hit into the side of my car causing about 180,000 baht of damages.
Witnesses claimed I was making a right turn when he hit me on his side of the road and a police officer at the scene agreed with them. I pointed out that the broken glass of his mirror was clearly all on my side of the road but they wouldn't hear any of it.
My own insurer was ready to side with them but I wouldn't and the police officer said I needed to go to the police station as there were injuries. I attended the station and produced dash cam footage confirming what happen. When the other party arrived (he went to hospital first), police fined him 400 baht for dangerous driving and he apologised to me.
Second situation, a truck driver on the Chonburi bypass cut across 3 lanes into the right lane straight in my path (just before the bridge where trucks hate being stuck being other slow trucks), I managed to brake in time but because of his sudden jerky maneuver, his uncovered load of rocks fell all over my car damaging my windshield and causing significant paint damage. He attempted to flee the scene so I called the police and we managed to stop him.
The truck driver denied what happened. Despite me saying I had dash cam footage, police and my insurer was ready to concede saying it would be difficult to prove liability since there was no vehicular collision. We went to the police station and I showed the video and the truck driver was fined 400 baht for dangerous driving but still refused to accept responsibility. The police told him that if he didn't accept liability, they would fine him for driving with an uncovered load which was a much higher fine. He reluctantly accepted liability.
Moral of the stories is, get a dash cam.