If I were on patrol and had to fill my quota, I would concentrate on skier code #4.
"Whenever starting downhill or merging into a trail, look uphill and yield to others."
I ski pretty fast on groomers and try to avoid crowds at all costs but I still see violations of this rule causing collisions or near misses all the time.
For example, yesterday I stopped above a steeper pitch as I usually do to wait for it to clear. I ski fast but am not usually in a rush. One person stayed on the pitch, stopped about half way down and to the side looking down hill. I waited another minute but new skiers were aproaching from above so I pushed off and kept laser focused on them. Sure enough, as I approached they pushed off, never giving a thought to looking up hill. Makes you wonder if they were parked on the side of a busy freeway if they would just pull into traffic.
The motorcycle analogy is so true, ask any rider what a car stopped on a cross street or driveway will do. Usually they wait until you are sure they must see you comming and then, at the last second, they pull out in front of you. You could set your watch by it.