1. They install a mobile modem (with sim) into every tractor
This, I expect. It's what auto manufacturers are doing.
But tractors are not meant to run where cars do, like cities, villages, crowded highways...
I mean, could you expect tractors to stay in an area with stable mobile coverage? Or aren't they meant to run on vast rural emptinesses where you haven't (almost) any?
In any case, a Faraday cage would help the owners in protecting their properties.
Again, a tech savvy owner has plenty of means to do it.
"There is no distinctly American criminal class except Congress." -- Mark Twain