That's different. It is well established that speeders get fined in every state in the country. Furthermore, special fines are disclose by sign. An example would be the work zone fines for speeding. The purpose is to get people to slow down, not to collect the fee. It is not well established that skiers get fined - especially $1000. Most ski areas do not have this policy and this policy is new for Washington State. I'm just suggesting that the deterrent would work better if people knew about it. That is the purpose right, do discourage people from skiing closed areas.
To me your point is that it's against the rules, so don't do it. That is obvious. The fine is not.
Do you really need to be beaten over the head with it? You know you're doing something wrong by blatantly ignoring the "closed" sign. You know there is some type of consequence, which could include but may not be limited to losing your pass, having to pay thousands of dollars if you require rescue and being fined. You make the decision to do it anyway. Maybe, you lose. You get fined.
It's not brain surgery. Every state has its own laws and fines for different types of activities, and last I checked "there weren't a sign splainin' it" is never a defense.