the point is, money stops being worth anything in this scenario. you can't eat it and you can't drink it. money is based on trust and when civilization collapses, trust disappears.
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.
Saying that 90% of crops would fail is kind of an over statement. Organic farms that don't use fertilisers are quite successful. The issue is planing and sowing, all of which the extra man power can assist with. Instead of a tractor you have people.
All that's needed is a plan, where farmers us the extra labour until machines can be gotten back on line. No need for a lawless society.
Cuba is an interesting example of a place that had to rapidly adopt a low-power lifestyle, and they actually seem to have done it with grace. There might be a good case there to study for clues about what works. They have the advantage of not having to contend with long, cold winters though, which is a critical difference for most of North America.
I would imagine that secretly farmers want other local farmers to not do as well, so that there is less competition for their produce, however you'd know better than me.