I used to live in Charlotte. Always wondered why the traffic was so uniquely awful there. Today I got my answer.
The suburbs follow a similar pattern, but appear to be at slightly different angles. I'm not sure if this would explain the even distribution of road orientations.
That's my point. The city is fragmented into tiny grids oriented at random angles. Wherever these grids meet, there are odd intersections and traffic patterns that are difficult to optimize.