Iv had cameras front and back on my car and my bikes for years. Iv had success on 2 occasions at winning after road crashes where the other drivers denied being at fault when in fact they were and once when I was on my triumph at a petrol station and had a car drive in the back of me to nudge me out the way (on purpose as they wanted to use the pump I was at )
They are so cheap to buy now that I don't understand why everyone don't have them.