I've always linked my inability to navigate to my inability to visualize things in my head. Even in the area where I've been living for about 15 years now, I still struggle to determine routes if I don't travel them very regularly.
This afternoon, we drove to a place in the city nearby. By now, after so many years, I can guess which exit to take, but I don't know whether to turn left or right at the end of the exit until I'm at the end and recognise it from previous times I've been there. But I can't picture it in my head beforehand.
I also have aphantasia but can navigate just fine. I read a comment on here once from someone with aphantasia that couldn't navigate in the real world, but they worked in network admin and knew that layout just fine (knew where everything routed and what it connected to etc). I pondered that if they could remember cable routes, why don't they apply the same mental map to roads? Roads are fixed and have a beginning and end too! But they reckon they could not. So it's a strange problem.
I think the challenge is relating your current locatiom in a 3d environment to a top down 2d map?
The 3d environment is full of noise and info which is a lot to take in while something like routing is very simple, and you don't have to convert your own placement in 3d map to 2d.
Also routing likely has good intentional reasons why something follows the other. While roads have evolved more naturally throughout history.
This afternoon, we drove to a place in the city nearby. By now, after so many years, I can guess which exit to take, but I don't know whether to turn left or right at the end of the exit until I'm at the end and recognise it from previous times I've been there. But I can't picture it in my head beforehand.