This is a complicated question, and as I mentioned, I'm happy spending a reasonable amount (subjective measure) for insurance. The way DAV does it in Germany is great.
Let's consider the limited/simple scope of resorts being liable for rescue costs of skiers who leave via backcountry gates. If that happens, one solution is to hire an actuary for 5 minutes to calculate the yearly SAR costs for those who leave via the gates. Estimate number of skier-days out of those gates. RFID tag those gates. Require all BC skiing from the resort to access the BC via gates. Charge a tiny fee for the RFID gate access on your pass, many of which are already moving to RFID anyway. I'm guessing the extra cost per day would be something under $1-- and the legislation that requires the resorts to pay could also require that the extra BC access fee is limited to break even costs for SAR outside the gates. Create a fine for not buying the access worth $100, and charge anyone who sneaks through and ends up needing SAR the full cost of the rescue (outside what their own insurance covers, obviously). Nobody needs to actively enforce the $100 fine beyond patrol keeping an eye out for folks skipping the gates. Hell, if you get away with skiing the BC from the resort without buying the access who cares... the point is that the resort will have taken steps to make it exceedingly clear that you pay for this access and if you didn't pay you're in violation, meaning SAR is at your own cost + the fine once you're rescued.
Of course it would be even easier to figure SAR into every ticket price, which must be like $0.10, and easily absorbable in the days of raising ticket prices by a couple bucks each year anyway.
Does anyone with any REAL knowledge of the statistics want to weigh in? All we really need are: skier days on a medium/big resort over an known time period and SAR costs from the resort over a known time period. They can even be different time periods and we can normalize them for a back of the envelope calculation of how much it really costs to run SAR from a resort vs skier days.
This doesn't do anything to answer who pays for what in the real BC. And how costs may be differentiated by land designation: private, public, national/state/local park, marked route/non-marked route, etc.
I think the emergency room analogy (if it even is an analogy really, since it's an integral aspect of post-SAR) is worth considering. I don't think anyone is going to make SAR a pay-first-to-play service. You get in trouble, and SAR comes and gets you if they can. The bill is dealt with later. Kinda like walking to work and having a heart attack or getting hit by a car. I don't think we'll see the scenario of, "That guy isn't covered. Easy rescue, but he's gonna just have to die since he is out there beyond his means and coverage." And post-SAR, if the rescued need emergency medical attention, they're going to the ER.
What that results in are costs that SOMEONE... EVERYONE... is going to pay. Just like when someone walking down the street gets a heart attack and i) isn't insured, and ii) can't afford out of pocket ER costs. As another poster mentioned: Unless we get to such a socially and legally individualistic point that we let people die in the ER because they don't have insurance (which will never happen), we're already paying for the uninsured. There are no two ways about it. So it behooves us to get as many people into the system as possible (the mechanics of which are contentious; see: health insurance debate).
This is an ideological and practical debate. We're not talking about health care, which every human in the country will use. We're talking about a service only a small % of the population even engages in activities that might require it-- and an even smaller % actually uses. We might as a society look at the costs and say, "SAR costs $0.00000001 per year per citizen so we can just absorb it." But in such an ideologically driven time, no matter how negligible the cost (and I don't actually know what the cost is) there will be massive push-back. The other option is to make insurance for these activities very cheap and easy for private citizens to buy for general coverage, or build the price into a ticket/park pass, parking fee, whatever as much as possible.