If your car is undrivable they can charge you to repair anything you damaged, such as the Jersey barrier. If you can drive your car a few hundred feet after the accident (cracked radiator) they can't get that money from you and don't care.
I'm curious how this works. As far as I know in the UK if you damage street furniture (signs, street-lights etc) with your vehicle then you're responsible (or your insurance is) for paying for it. Surely it shouldn't matter what state your vehicle was in at the end of it, just the damage that you've caused?