Unless someone prove me wrong, the problem with collision detection is not that noone would make one, but that it won't work properly without core integration.
Here's an example for you:
YouTube - Visosad 070426 vessel-vessel collision detection demo
And there is no way to stop that shaking. Any time acceleration scatters all vessels, since there is no core to keep them in place, like normal landed ones.
True, some special cases might work believably, like Shukra station, but it's still far from any kind of perfection.
The trees are possible.
Non-boring trees, however, is not that easy.