So what's the conclusion here? Who needs to do the double check? The coroner, because the event did not happen thus the passengers are alive and stationary due to lack of a driver or the fire department because there's a driver on the drivers seat but they missed it?

To me, there's lots of possibilities. Driver couldn't open the door after the crash, so moved to either the passenger or back seat to try and escape...but failed. Or, third person was driving, fled the scene on foot. Both kind of unlikely. But how likely is it that they circumvented the seat belt, put a weight on the seat, and kept torque on the wheel, and then engaged autopilot?

Whatever happened here is going to be something weird and unusual.

Of course a full investigation is needed but it seems like a good case to use Occam's razor.

People with Tesla's often use defeating devices to overcome the measures against unsafe use, there are many videos on Youtube of people doing just that. It's colloquially known that people are attaching small weights etc in order to do that, pretty basic stuff. Also software often has bugs, it's known for Tesla to release software under the "not ready for daily use, use at own risk" pretext. There are also previous known crashes due to the failure of Autopilot as well as videos showing failure of Autopilot where crashes were avoided thanks to human driver sitting in the drivers seat.

The other alternative is that these people acted unreasonably, crashed the car, failed to exit but changed seats before perish and the professionals who reported in and investigated the situation couldn't tell that.

Which one is more likely o have happened?

>Which one is more likely to have happened?

No idea. "Professionals couldn't tell in the immediate aftermath" isn't that odd. Especially given the state of the vehicle.

Nitpick: there's a difference between "will not activate" and "will deactivate if it was already active". (For the record, my opinion is that this was entirely the driver's fault and not Tesla's fault at all.)

Autopilot also supposedly wants the seat belt buckled and weight on the seat, right?