Control, privacy of information, possible identity theft, possible fraud.

How do you add to or invalidate any single license on a multiple license card?

The technology exists now, and ID technology is headed that way, although it's more likely to be used first in "smart" credit/debit cards than in drivers' licenses. The cardholder's biometric information- fingerprints, iris patterns, and/or facial biometrics, are contained in a chip imbedded in the card itself. At point-of-sale or point-of-identification, a fingerprint, iris, or facial recognition device compares the user to the information contained in the card. It's not really a stretch to imagine a "multicard" with these built-in identifiers.

Currently, there are 3 types of systems, the cheapest offering the least level of security, where the information is downloaded from the card, and the most expensive offering the greatest, where the comparisons are done within the card itself.

i'm unconfortable already with all the information in the system on myself. putting it all together makes your personal information even easier to obtain.