Re: anti-collision
Much to some people's very short surprise, trees don't snap; it's like hitting a motorway bridge abutment
I've seen the results of crash-test comparisons between lamp posts and trees. Given the choice, I'd really, really rather hit a lamp post.
(I'd like to point out at this moment that the only thing I've ever hit on the road have been other vehicles. And none of them have been over 10mph. Even that time I was driving up the dual-carriageway near Watford, coming over the hill where the limit went from 70 to 40mph with about 200m until a set of lights. I sensibly put my foot on the brake to slow down only to have it go flat to the floor with no resistance. Amazingly, a Mini Metro[1] gearbox can survive going into 3rd at 70mph and 2nd at 50mph. And the handbrake can stop you surprisingly quickly as long as you stay in a straight line.)
[1] Owned by my mother. It went surprisingly fast if you switched off all vestiges of mechanical sympathy. We sold it shortly after that (and told the buyer about the intermittent brake problem - which my mother had known about but forgotten to tell me..)