Airlines seem to be an interesting outlier where people expect the carrier to put you on another airline subject to whatever desires the pax has at the time of rebooking. Is there another industry like this? If your account gets the flu is there a bill of rights that says he has to get the account of your choice from a third company on your file?
I agree it's desirable for the airlines to do this from a customer service perspective, but it's not clear that it leads to systemic benefits that outweigh the costs to legislate it, just like people want a bill of rights that guarantees larger seats in economy, but most economy passengers' revealed preferences are for the cheapest possible fare. Remember AA removed MRTC when they found that passengers were not willing to pay.