It's easy to place all the blame on the shooter but you're basically ignoring the other 999,999 in a million of these situations where bad stuff happens that don't escalate to this point by doing that.

You can't just say that the people actually doing the thing (whatever that thing may be) are in the right because they are doing their jobs otherwise they become a black hole for infinite liability. You need to accept that the dead person was wrong to be there collecting that package at which point is becomes a question of who dispatched them (obviously not themselves in this case) on what grounds and under what circumstances, etc, etc and how did it lead to this failure.

Think about this like an industrial ancient, not some heartstring grabbing rage bait. There will always be crazy old men. Sure, send him to prison or whatever but how can the chain of events that lead to this particular crazy old man killing someone under these circumstances be broken. Uber needs to tighten their shit up, so does the phone system, etc, etc.