The trouble (well, one trouble) with forcing stations to air everything they buy is that there are a fixed number of hours per day. Now, if they normally are off the air a few hours, that helps. Or they can cover informercials, but those, I assume, would then also have to be run elsewhere, refunded, or both... and either way, if something major knocks out a large enough chunk of the day there'd still be no room.
(I for one long for a day when *every* new show, once the original broadcast has finished or would have been if it aired at all, is available streamed online, or at least by something like the iTunes store, indefinitely. With older material added as it's rerun or whenever someone feels like it. )