Everybody assumes that in an end of the world scenario that we all end up fighting for food, however the better plan, and to be honest the one that served society well in the past, was that we become farmers. Without tractors we'll have plenty of farmland that needs manual labour.
It would be nice if it was codified into law that our fallback plan was to redistribute farmland. Then there is no need for roving biker gangs fighting for the last can of tuna. We'll just step away from the now dead computers and pick up a hoe.