You are right. If we had more donors this would be less of an issue.
Almost all organs harvested in sparsely populated areas are sent to biggest city hospitals,, and are not made available locally to the many hospital programs that could use them effectively. Worse, some cities like NYC train their EMS on thinking “potential donor” instead of “patient”.
NO way I would sign my card. It’s nuts to give them the slightest incentive to go ahead and write you off. If a person wants to donate, the best way is to tell trusted next of kin and let them decide when you really are beyond recovery.