As I've said a couple of times on the 'motor vehicles crashing into buildings' thread, while crashes against a wall now rarely seem to result in serious injury to the vehicle's occupants, crashes against trees generally do. That the force of impact is distributed over a smaller area, plus the possibility of the vehicle being spun around, are probably largely responsible for that. (I don't really know the physics of that, so if somebody knows more, please explain.)
Here's a terrible crash against a tree:
https://www.theguardian.com/uk-news/2019/aug/24/essex-car-crash-driver-arrested-two-die
As I've said a couple of times on the 'motor vehicles crashing into buildings' thread, while crashes against a wall now rarely seem to result in serious injury to the vehicle's occupants, crashes against trees generally do. That the force of impact is distributed over a smaller area, plus the possibility of the vehicle being spun around, are probably largely responsible for that. (I don't really know the physics of that, so if somebody knows more, please explain.)