I'm old enough to have a dim memory (true? who knows) of the Time Before, when airlines would readily book you on another carrier if there was a problem with your flight. I don't mean pre-deregulation, when a ticket was basically good on any carrier, I mean after that when flying was still not totally horrible.
I've long been curious why airlines don't have a funny money system for rebooking you on another carrier. The obvious reason is, of course, that they've decided it isn't worth it, but it's still puzzling to me.