Chip,
Interesting I was not aware of NC doing this.
Here in Virginia they now require anyone who has a classic car to fill out a form (have it notarized) to attest to the fact that their registered classic/vintage/antique car is not used as a primary vehicle by the owner (it must only be used as a low mileage, collector car), if the form is not filled out and sent back by the end of the year, the owner's classic car plates will be terminated by the state of Virginia.
Also when I purchased three years ago, antique/vintage license plates from the Virginia DMV, the cost (one time only) - $12. When I purchased plates for another classic car back in July of this year the cost was $50 (one time only). I don't expect it to stay at $50, since fees and taxes always go up. We as citizens must tighten our belts but government never does. It's always a one way street.