I don't think merely looking at the total number of skier visits and comparing that to the number of in-bounds avalanche deaths, then concluding that the chances are less than winning the lottery is really a correct way of looking at it.
What you really need to look at is how many people are skiing at your resort on the powder days. Then look at how many people are catching first chair on that day, or first in line for when they drop the rope on terrain, or the like.
The 40' slide I mentioned was triggered at Monarch 2 years ago. It was about a 16" powder day in March, and if I recall, it had gone about a week with warm temps before. Heavy wind, continual heavy snow, and lots of wind loading. We were on a slight upwards traverse to get access to two of the bowls, and the traverse had been completely blown in with snow and very hard to make any headway. We had made several laps, each time taking the traverse a bit further than the last tracks and dropping in off of some minor cornice areas.
After several great laps of this, we got for enough up the traverse to get to the next bowl over, which had been unskied because the traverse was so drifted over. Drop off the cornice, and it fractured and went.
The message I am getting, now that I understand the potential risk of getting caught in a slide, is that if you are the skier pushing to find the untracked and are consistently getting first tracks, it doesn't matter if there are 2000 other skiers there skiing the groomed runs, sitting in the lodge, etc. If somebody missed something, and you are the first person hitting a lot of the unskied terrain, you are the one it will happen to.
With regards to the avy I mention above, I am sure ski patrol evaluated the run at the beginning of the day and didn't see a problem, but the snow continued to fall and get wind-loaded throughout the day, AND completely unskied, and by the mid afternoon, was ready to let go.