I had read somewhere once that if the battery case is warped or damaged it's pretty much an automatic write-off. Any deformity to the battery pack means you have no guarantee whether the batteries are still good without opening it up to look, and who's qualified to judge whether the damage is compromising? There's a few videos available of removing the 3's battery pack, but it generally means major disassembly, plus a lot of professional manual labour - so by the time they pay for that (and the chance of replacing the pack) it's simpler to write it off.
I'm impressed if the 3 took that heavy a crash without bending the battery case.
I don't get it - the other car passed you on the left, so his passenger side should have been totally crushed? You said it was a backwards (RHS Japanese) drive, so the damage should have been to the driver's side for him? What did I miss - did he carrom off and hit a post or something? And I assume the video at nigh will show the lighting from your signal, so he should have known you were turning left. Very not-too-smart maneuver.