My examples for taking head/neck shots.
1. Deer standing looking straight at me. I will aim right in middle of face or the neck.
2. Deer standing looking straight away from me. I will aim for the area of the atlas joint. Bullet drops or strikes slightly higher it is still a clean kill.
3 & 4, Deer lying down, repeat as above.
If the animal is feeding and grazing with the head down, then I agree the likely-hood of a head/neck shot presenting itself is very slim however, a whistle, call, bark or even a shout at the animal will often present a shot like example no.1. Although the base of the neck is a fairly immobile area as is the rest of the animal.
My point is and it mirrors some of the comments above, not every time will a deer present a suitable target for head/neck shooting. As has already been said, there will be another day if this is the practice you employ. I have seen no more deer wounded either using this practice than when compared to the years I would generally have gone for heart/lung shots. Not just my practice but my stalking mates also. It had nothing to do with game dealer demands. It was to prevent deer, in particular Sika, running off into woods and making extraction/follow up too difficult. Both of us have GWP's trained in following up. Both of us would generally use a bullet of fairly rapid expansion. Currently a Sierra Gameking HPBT. They have a tendency to cause the kind of damage that allows for an inch or so of error and still cause fatal damage.
I would NEVER criticise a stalker who says that they always go for heart/lung shots as that is where they are comfortable in aiming for. Mind, when a couple of friends wanted to come out and assist on the Sika cull they were told that unless they were confident in shooting as I have described, then not to bother.
It is bad enough trying to recover and extract your own deer but I get a tad ****ed off when I have to find one for someone else, under a shut in wood, in the dark, by torchlight, now raining, pine needles down my neck, tired, moaning wife on the mobile saying dinner ruined....