I had my rear door pop open several times on the old P10's, usually it had to do with spring adjustment and worn out latches. If that driver was going to his delivery area or returning to building his chain should be latched for sure.
The cameras were great at catching that the door had opened, or that you left your handcart on the bumper (or DIAD!)
We've had the guards not properly close & chain our doors on the trailers sometimes when we leave (we close them but they check to verify it's empty). They usually do the whole process when it comes to closing LC or FSTZ etc swing doors for a rail seal, and I've had several where they sealed the trailer and didn't latch the top properly.