The thing is only 4 or 5 states are currently issuing enhanced driver licenses that meet the legal definition of one. There has been a lot of extensions and delays so that a regular driver license and original or certified copy of the birth certificate are still accepted for closed loop cruises. Otherwise they would be requiring someone from, say Texas, to get a passport while someone from NY State (where they have issued EDLs) to not get a passport. There are also issues with people with valid driver licenses issued before the EDLs came into effect.
The whole thing is a mess. They never should have made the closed loop exemption. All it did was add needless complexity to what should have been a cut-and-dried thing.