Look, yes, many people have taken bad shots. The difference is few are rarely THAT bad.
True, you virtually never find a deer shot twice by two different hunters at different times that is still alive with nasty wounds. Yep.
However, the shoulder shot on the deer doesn't appear to be a hugely terrible shot. A couple of inches over and that could have been a very dead dear.
Let's say the shot was at 100 yards. Flight time on a bullet at 100 yards is going to range from about 0.10 seconds to 0.13 seconds on most of your typical hunting calibers. That is just flight time. A good bit of motion can happen in that short people of time. Add to that the delay of time from when your brain tells you to act and your finger pulls the trigger which will add 0.15 to 0.40 seconds depending on things like your age (younger people have faster reflexes, generally speaking). All that had to happen for that shot to be off is for the deer to start to take a step AFTER the hunter decided to pull the trigger and the bullet will be off the mark and it could be by several inches. If the hunter was using a bow or subsonic ammo, the deer may have been reacting to the sound of the shot and starting to move before the bullet arrived.
Furthermore it's the lack of follow through to harvest that takes the cake for me.
One of the really interesting things about hunting is how hard it is for hunters to find ambulatory animals that have been wounded. Some can find them after they are downed, but not all. Hell, there are plenty of hunters that can't find downed deer.
Maybe you shoot the deer and it runs. Well, obviously, you can't shoot it again if you are some hunters. Why? Because shooting running deer in unethical, or so I have been told in this very thread.
With that said, the deer runs off property onto private land, as in the case here, following through to find an ambulatory deer becomes that much more difficult.
Part of hunting is knowing when and when not to shoot. Determining the odds of a shot leading to a good kill or not.
I am totally amazed by the number of hunters who were never newbs or otherwise inexperienced. They know everything before the hunt even starts. My hat is off to them. It truly is.