The US DOT rules today specify 200% of fare capped at $675 for a 1-2 hour delayed arrival at destination and 400% of fare capped at $1,350 if greater than 2. Practically speaking, a passenger does better under the US rules on a long-haul flight.

But, the real key is that the US rules not only require the carrier to seek volunteers before involuntarily denying boarding and also require the carrier to deny boarding in an order specified in advance. Thus, award tickets, fare basis, and status are all valid considerations, but also known in advance.

Seeking volunteers is a win-win-win. The carrier need not anger a passenger, a passenger who would have been denied boarding but wishes to fly may do so, and the passenger who would not have been denied boarding, but is pleased to accept the extra day or two in a hotel, is quite pleases as well. That $1,350 may seem like a lot of money to some, but it is a pittance to someone with an important meeting.