About 8yrs ago was in a works van in traffic, stationary even, car behind bangs the rear bumper. We didn't even notice, just heard a bit of thud, saw a guy get out his car behind as we were wondering what the noise was. I got out and he was all apologetic, turns out his foot slipped on clutch. I didn't care, quickly exchanged details, i think we discussed about cash at some point also.
Few weeks later i think, lady rings me asking about it. Yeah i'm fine etc, no i don't want to claim for whiplash as it'll effect their insurance and nothing happened. I remember her replies being along the lines of it won't affect their insurance and i should claim, i remember raising my voice and hung up.
When some people get a smell of a bit of cash...
But if i had a huge smack up the rear on a motoway or something i might behave different if i felt the person crashing into me hadn't made a normal accident/ fair lack of judgement, like the poor guy above in my post.