I think the bottom line is that it's somewhat at the discretion of a few lead officials at NCDOT since all of it can be classified in the rural category because of the tree buffers on even the I-440 Beltline which probably should get lights before Eastern NC corridors. It's the same as with overheads on streets around interstate junctions. Sometimes they get overheads, sometimes just small shoulder signs.
You can see over the past 20 years that they will add a few lights here and there like on I-540 and the Fortify rebuild, but they are so strained already with funding that must be spread thinly across the state. Plus someone has to pay the monthly bill.
I'm sure it's a lower priority than reducing dangerous intersections or relieving bottlenecks across the state.
Only Charlotte is fortunate enough to get continuous lighting on freeways and it went for years broken and unrepaired which was a blight on city that's growing and shouldn't have had to endure it.
Always suspicious of Charlotte being shortchanged by the state and falsely thinking that Raleigh received preferential treatment by lawmakers, a Charlotte local news station sent a crew of reporters on a trip to Raleigh hoping for footage of Raleigh's freeway lights working perfectly while Charlotte's remained broken for years.
But as with so much that Charlotteans wrongly assume about the rest of the state which they look down on by the way, their trip was a fool's pursuit as they realized that Raleigh's freeways don't have any lights at all. This was about 10 years ago.
They also think that Raleigh has more concrete freeways which is absolutely not true. US1 is the only one I can think of while I-85 and I-485 have many more miles of concrete pavement than in the Triangle.
I'm all for lighting as much as they can, but most of the folks decrying the lack of lighting in NC have less than stellar eyesight so that has to be accounted for. I used to have 20/15 vision though now it's decreasing after passing age 50, I've never had a problem seeing.
Atlanta has no lighting on at least 50 percent of its freeways, but here whatever town is nearby can install and pay for lighting if it wants to.