Tag -- great thoughts, good questions!
My point about the sublimation of Petrick's conduct (do not stop at "Negligence," do not collect $200, go straight to "Recklessness") has to do with the character of the risk. I would call it simple negligence if Petrick had merely been going say, 10 mph, and knocked Mastro over without any injury to speak of (other than to Mastro's or Petrick's own pride). Of course, this becomes a bit of hairsplitting -- that's because in most tort cases, universal legal axioms are hard to come by because bizarre tort facts rarely repeat themselves.
Maybe I was too quick on the red light/green light analogy. Let me try to explain it -- perhaps I will end up contradicting myself... You and Herman are correct that in the typical law school example of RIL, when a barrel falls from a window in a 2d story warehouse, and the witnesses could see no agent on the 2d story to cause the barrel's fall, and the barrel strikes Peter Plaintiff, a pedestrian passing below, the liability simply is assigned to the warehouse because there's no other explanation. The warhouse regularly houses such barrels, its window was the only one open above the sidewalk where Peter Plaintiff was injured, and the barrel clearly fell from above and nowhere else.
In Mastro's case, the analogy isn't perfectly linear, but I think it holds. As the uphill skier, Petrick has the obligation to watch out for those below him. As we saw with the Hall/Cobb collision, the care Petrick owes to Mastro (and other downhill persons) includes not only avoiding those he can see, but also factoring in the risks associated with speed and terrain. In Hall's case, that meant accounting for someone being on the other side of a blind knoll. In Petrick's case, that included being aware of Mastro's position and doing the mental calculations of the rate of approach and the time/room needed to avoid colliding with Mastro.
RIL is not strict liability. It is something that posits liability, yet is susceptible of disproof. Under my analogy, in Petrick's case, his collision with a downhill skier resulting in severe injury to that skier is a RIL recklessness assignment, UNLESS he could disprove his recklessness by showing that he proceeded with due care but something intervened -- hidden ice patch on an otherwise perfect condition day, Petrick's board delaminating just as he neared Mastro, etc.
That may be a bit fuzzy and maybe even tenuous to some folks, but I think it's a pretty fair analogy.
Herman, what do you think? Am I heading back down the driveway to The University of Stupid?