We're so spoiled by having freeways that we probably don't realize just how messed up our other roads would be if the freeways get blocked.
We live near a river which creates some unusual situations due to the limited number of bridges. I was driving near the river one day when the local freeway got blocked; I don't remember why.
The side roads were filled with cars and traffic took hours to clear. I wouldn't just assume that any particular side road will be clear.
Freeways are the only place where it is practical to drive 60 miles per hour. If one is limited to ten or twenty miles per hour anyway, then almost any road will do. The hordes will probably take the roads with the most homes along the road, looking for opportunities.
Yeah, I can see where you are as making a difference. Here in CNY, the backroads would be the way to go.
But you do have to know them.