It would be interesting to learn how many of the "rural" people on this forum are more than 100 miles from a population center of 100,000 and more than 10 miles from a national or state highway of 4 lanes or more total.
Most people drive their cars around on near empty. When shtf, there will still be some people with 5 gallons of gas in the tank - enough to go 100 miles.
Most people are lazy or physically in bad shape. They don't exercise. However, I would let some of those 100,000 who had the 5 gallons of gasoline go the 100 miles and then have to walk the last 10 miles on paved road. Notice that I didn't make any reference to dirt roads, snow, ice, local blockades. And, I will grant you that if a lot of people tried to walk 10 miles on a paved road with no water, most would not be able to walk it.
The problems of the rural people are quite simple:
1. the people coming to their area are not the poor urban who ride buses;
2. the people coming to their area are suburbanites who have the money and as a consequence have weapons, perhaps a background in scouting and may have served in the military. This, of course, would not apply to poor urban youth.