Its a good thing too that all the world's best marksmen magically met each other in the zombie apocalypse. I've never seen so many people who could hit so many moving targets with a headshot, every time, from a moving vehicle in a field... AT NIGHT.
Now, I get the whole "it's a TV show - its not real - it would be boring to watch people take shot after shot and not hit anything"... I get that. But the zombie thing has been done so many times. People have higher expectations now and "realism" is the best way to suck an audience in to an unrealistic scenario. I would like to see a little creativity and not just the same thing I've seen in every other zombie story...
Well... yeah... it is actually a TV show... made for your average zombie audience who's grown accustomed to these things in every zombie movie we've had so far. Most of the audience has never picked up a gun before.
In reality, if we had to shoot zombies in the head with a handgun from a distance, we'd be hosed.
People don't realize just how small a head is... or how hard it is to hit while they're moving.
Even police would have a problem. That's why you aim for the center of mass... it's much easier to hit. No matter how much you line up your target, outside factors cause your body to move. The slightest movement on your part, will cause a huge displacement on where your bullet lands.
But I think right now we have:
A sheriff who was really good at his job
A natural marksman who discovered she had a gift she didn't know about
A guy with a history we don't know about... no idea what Hershel did when he left home other than that he took up drinking.
Keep in mind that all these people are also properly motivated.
It could be a case of survival of the fittest. Those who don't have those skills either stay close to those that do, or die.
Still... all zombie movies seem to make it too easy. Same with swords or knives. They always seem to take the head clean off. Usually to get through a neck, you have to hack and hack.