...Is it really an autopilot crash? Or some guy who, unfortunately, wasn't paying as much attention as he should whilst driving a 2 tonne hunk of metal around other human beings?
Well, you you read the statement in the summary:
The NHTSA report said data from the car showed that "the driver took no braking, steering or other actions to avoid the collision". Bryan Thomas from the NHSTA said the driver should have been able to see the lorry for seven seconds, which "should have been enough time to take some action".
The NHSTA is saying that while Tesla's autopilot features are made to help avoid collisions and improve safety, they are not legally responsible for keeping a driver safe. The driver still is responsible for operating the vehicle, including in emergency situations. The owner here did not make any attempt to avoid the collision but should have been aware of the situation. Either he was being an inattentive driver, or he deliberately failed to take action, expecting the Tesla system to instead. In either case the Tesla system is not the one to blame for the accident not being avoided.