Another way to imagine it is think roads in the 30's and 40's. Highways as we know them were just in their infancy.
Cities and towns most certainly had "dirt" roads although not likely downtown but in the outer areas for sure. Many 3rd World (although I dislike the term) Cities still have similar roads even today. I've been down "paved highways" that could be never called as such here. So I guess it is relative.
Perhaps if there were no lines on the paved roads??!!
Ostfront roads in the wet seasons could be better represented by strings of mud hexes to be sure. AND it is possible with patience and the map editor to make earth paths etc.
Just random thoughts.
Bob out