If I can spend 100k on a tractor cause 100t of pollution or 200k on a tractor causing 50t of pollution I will obviously choose the firmer tractor as the rest of the world pays the price of the extra 50t of pollution.
If the externalities of that carbon generation are priced in I end up paying more for the polluting tractor so I choose the less polluting tractor and make more money.
For farmers today, the choice is more stark.
I can only speak to small and medium farms, but if we're talking large horsepower cultivators / row farming, It's really a choice between keep my old pre-emissions diesel/buy a pre-2006 used tractor from auctions/marketplace for 50k, or double down and lease a 250k-400k new mid-size tractor.
You make it seem like many farmers have choices, but old "dirty" tractors are the only financial options for many without signing up for indentured servitude to JD/Case/etc
So they externalise their costs and get other people to pay?