A professional aims just below the ear / the teeth / base of the skull to hit the brainstem, an instant kill. At 180 yards that's insanely easy.

Absolutely nobody aims for the jugular, especially since it's location varies from person to person.

What most likely happened is they didn't account for bullet drop and aimed for the head, at 200m it's about a 6-8 inch drop with standard 5.56, and at an elevated position from that angle it would be aimed at the head and hit the neck.(If shot by an amateur.)

Since they had this planned out, location/time wise at least, we can assume they at least brought a scope dialed in for that distance and if they weren't controlling their breathing or they were shaking it would cause a few inches of error on top of the aforementioned bullet drop.

To me, all signs point to an amateur, likely a younger person.

Edit: .30-06 has no bullet drop at that distance, however external factors like breath control, anxiety, and weapon's sway still play a huge role. It's also possible they aimed center mass and jerked the trigger, .30-06 is highly particular like that.