The user claimed that he stood in front of the the vehicle for a good minute and that it crashed on its own accord after he left it and went into a store. However, in a letter dug up by The Verge, Tesla says the vehicle logs show that the driver deliberately initiated Summon mode and received several warnings and messages. It then started moving just seconds after he exited the driver-side door.
Tesla previously issued a "dead-man's switch" safety fix for the Summon feature that requires a user to continuously press the key fob or smartphone. If you release your finger, the car stops immediately. Reddit users point out that the feature is on by default, so the Utah driver must have disabled it. In that case, he would have activated the feature by double pressing the "park" button, as Tesla says, and to stop it, he'd have to press a smartphone icon or key fob button.
By forcing users to choose whether the vehicle backs up or moves forward when summoned, the new feature may have prevented the Utah accident. Either way, sensors are supposed to stop the Model S immediately if they detect obstacles around it. As is clear from the accident photo (above), however, the high position of the trailer may have eluded them. Tesla hasn't commented on the new feature, but we've reached out for more info.