I'm not trying to be snarky or argumentative, I really don't get what you're saying. Sometimes you don't have a reasonable choice other than working on a day off.

If the last leg of a trip is cancelled or delayed and I'm stuck in another city until my day off, they sure as heck can "make me" work on a day off.

I'm honestly not sure what's not being communicated here. This isn't a hypothetical "if it happens" thing, it's "when it happens", and that's why the contract has a rule about it. Who hasn't had a trip where maintenance and/or crew availability delays caused the last leg of the trip to be delayed long enough that the choice was to work on a day off, or not go home at all?