What about people who don't have a DL, but want to carry? One of my elderly aunts carries, but has simply never needed or wanted a DL. Also, what about people who have their DL revoked (for traffic violations), but are still eligible for CC?
Also, do we really want a federal middle ground to be the same for every state? In a national compromise CA would turn out a bit better, but wouldn't that be a bad thing for TX? Also, it could violate state's rights to govern themselves.