There just aren't many cars, thats really the answer. Theres a few videos on youtube of tourists/diplomatic staff driving down a completely empty 10 lane highway lol
https://www.boredpanda.com/blog/wp-content/uploads/2017/07/4...
https://www.boredpanda.com/blog/wp-content/uploads/2017/07/4...
I suppose it's also possible that (I think I saw it suggested elsewhere) the streets were cleared for the photo... and I didn't try to find out how these photos came to be.
#2 lower left corner
#6 lower left corner at least 4 people visible
#10 someone walking at the 'south' end of the road, cars; a man at the storefront a bit farther; some people at the crossing and at the other end of the road
#11 there is one on the left side
#14 around 10 in the middle of the photo, cars and probably people at the farthest end of the road
#16 a lot people actually, because it's some celebration, in the middle of the photo; a lot of plain clothes (or dark coloured uniformed) people on the roads (look at the bridge)
#17 around 20 people easily distinguishable, clearly some cars at the other end of the road
Sure, this is waaaaay less than needed to convey an image of a living city, but as other people say, there is a clear bias for this type of people-less shots at KCNA.
https://youtu.be/CDcfiEX__cA?si=tqSHZp2tsK_viRnA
Pyongyang by Guy Delislse also paints a charming if twisted picture of commuting in the city on foot.