a lot of little things I noticed on that trip that made me skeptical about ever being able to trust it to operate without supervision.
Yep. Mine has the original autopilot -- late 2014. The radar/software pretty much ignores static objects. I fully understand how that Model S ran into a parked fire truck a while back. It wasn't moving. But once the Tesla sees movement it does a pretty good job of following. Too good, sometimes. It seems to give more weight to what the car in front of you is doing than lane markers.
Has version 9 improved things for cars with autopilot II?