I suspect that you’ll find this particular voter role problem isn’t just unique to NC. It’s a local county function that has the responsiblility of keeping the deceased removed from the voter roles and I doubt it’s a high priorty in many of them.
With the advent of computers and the technology available it should be much easier to monitor the death records in each county and then have that name removed from the voter roles. Other records could be monitored such as Drivers License changes, marriage/divorce actions, felony convictions, etc. all of which could be used to help keep the voter roles more accurate and up to date.
When someone dies, a death certificate is filled out by the local authorities (sometimes Police, Doctors or Coroners) and filed with the NC State Department of Vital Records. I doubt it would take more than a few keystrokes for NC (or any other state) to figure out who has died in the last few years and remains on the rolls.