I'm not too sure the 3 foot height had anything to do with this accident.Not surprised. I still refuse to believe yo can program a computer to account for any infinite driving scenario. If they ccan't account for making sure the roadway is clear more than 3 feet off the ground, then we are still a decade away from being used for livery
The car may not "see" the trailer from a few feet away but it definitely should have seen it from 100, 200, 500 feet away where the three foot height should not have been a factor.
Apparently the Tesla comes with 12 sensors that "see" objects for sixteen feet around the vehicle. It also has forward facing cameras and radar units.
Even if the cameras couldn't see "The white trailer and brightly lit sky", the radar units didn't detect it.