I wonder if most states don't bother incurring the overhead of processing written tests if you already possess a license from some other state. I can't imagine road signs and rules differ all that much--if at all--and they figure you already passed the written test when you first got your license. After all, most (all?) states don't require you to retake the written test in order to get your license renewed. I wonder why North Carolina required it.
License Renewal For Senior Drivers Virginia drivers who are 80 75 years of age or older at the time their current driver license expires are generally required to renew their license in person at a local DMV office. The renewal packet will tell you which method of renewal you are eligible for. In addition to taking a vision test every time you renew in person (see below), you may in certain situations be asked to take a written knowledge test as well. Further, if your license has been expired for more than a year, then you will be required to take the vision test, knowledge exam, and road skill test. In preparation for this, you can review the Virginia Drivers Handbook and take practice tests before going for your license renewal. Renewing license before the age of 80 can be done online, in person, or by mail. edit to add: I pasted the above from a previous comment. I cannot find that information again. I did find that starting at age 75, you must renew every 5 years rather than 8 years. But on today's list of "Who cannot renew online or by mail," I do not see anything about being elderly. I'll keep looking. edit#2 to add: I went to the Mature Driver section of the DMV website and found this: Drivers age 75 or older must appear in person at a DMV customer service center to renew their driver's license and complete a vision screening or submit a vision report. But there's nothing about taking a Knowledge Exam. On the Mature Driver page, there's a link to renew your license online. I guess it will stop at some point when it sees your age.