I'm just over here wondering how they would control for that fact that people who can't self-navigate are more likely to habitually use GPS (rather than cause a

I'm just over here wondering how they would control for that fact that people who can't self-navigate are more likely to habitually use GPS (rather than cause and effect being the other way around, habitually using GPS leading to an inability to self-navigate, as they posit)? Personally, I use GPS almost every time I drive, so that I get advance notice of slowdowns and congestion. And yet I know the region I live in better than most other drivers I know.