Most places? It's required. As I recall, Krakauer couldn't climb without Outside Magazine paying his. The National Park service requires it of outfitters and the NPS itself has talked about requiring it of all climbers since 1993. Pretty much any park with a "climbing fee" (Denali, Rainier, Yosemite, etc) has the recovery insurance rolled up in it:

Where does the money from the climbing fee go?

The funds generated from Mount Rainier Climbing Pass sales are used to run the Mount Rainier Climbing Program. Funds are used to:

Protect the mountain's delicate and unique alpine environment

Staff the mountain's high camps with climbing rangers

Staff ranger stations with climbing rangers and other personnel to assist climbers in registration

Maintain a clean and healthful upper mountain free of human waste

Fly human waste off the mountain from collection points and dispose of it properly

Provide rangers who can rapidly respond to incidents on the mountain

Nanga Parbat? No climbing fee. Everest? $11,000 permit alone.

Tomek Mackiewicz raised 3200 euros to spend a month on Nanga Parbat. Divide that by the number of people and it's almost cheaper than getting sherpa'd up Rainier. You can barely get up Kilimanjaro that cheaply. But here this guy is, leaving his wife and two kids behind and staking about a week's worth at Club Med to hang it all out off of "killer mountain."

Thank you for exposing why this bugs me more than it should: it combines the "my friends are my life insurance policy" ethic of the irresponsible adventurer with the "pay me for my vacation" ethos of those fucks that always hit me up to "sponsor" their trek up Rainier.

It's two different ways to avoid paying your own way.