"The radar is used to detect other moving objects, not stationary ones. The reason for this is that the radar cannot tell overhead obstacles from those in the road so if it stopped for every stationary object it would be stopping for overhanging trees, overhead street signs etc."
... which is a valid comment at this point but should be load of hogwash.
The car doesn't just rely on radar. It has a ton load of other sensors telling it what is happening. It should be perfectly capable, right now, of working out a) what is a moving object, b) what is a stationary object, and *most importantly* c) calculating if any of these objects is in, or is moving into, it's projected 'flight' path.
A stationary overhead gantry, a lamp-post, or a tree branch hanging over over the road more than 6ft off the ground should be easily detected and *not* be a collision suspect for a Tesla. Nor technically is a car stopped in another lane if your lane is clear and moving, at least until it starts moving again or a human gets out of it at the wrong moment (identify: nearby stationary or slow object in what should be an open lane; reaction: proceed with caution, check speed, etc).
Something detected *directly* in the predicted flight path — or is otherwise calculated likely to be moving into it — *is* a collision suspect... ergo take evasive (whatever it deems that evasive to be at the moment, be it brake, slow down, swerve or whatever). This should not include street furniture.