Alaska Airlines must work a little differently since they offer a free round trip ticket (good for one year with no black out dates) to anyone who will volunteer to take a later flight. They always seem to get plenty of people to take them up on their offer.
"If the facts don't fit the theory, change the facts." Albert Einstein
"Of all tyrannies a tyranny sincerely exercised for the good of its victims may be the most oppressive" C.S. Lewis
Most airlines offer a free round trip flight within the contingent (spelling?) 48 states to use in the next year if you volunteer. If they force you to get bumped, you are not so lucky.