One common theme has been that farmers are by necessity highly independent. They can't rely on government services as much as city folk, because everything and everyone is potentially an hour's drive away. They don't see the effect of their taxes being spent, because their local roads are dirt roads, there's no traffic lights, no police cars[1] or ambulances zipping by on the regular, etc...
Conversely, they do get frustrated by the likes of the EPA turning up -- invariably city folk with suits and dress shoes -- telling them what to do. "You can't burn this" or "You can't dump that!". More commonly "you can't cut down trees on your land that you thought were your property".
Their perception of government is that it violates their God-given rights regularly and gives little in return.
The further the seat of power, the worse their opinion of it. Local councils they might tolerate, state governments they view with suspicion, and the federal government may as well be on another planet.
Hence, their votes are easily swayed by the "reduce federal government" rhetoric.
We all know this is as an obvious falsehood: Trump grew the size of the federal government with his Big Beautiful Bill! So did every Republican government before him for quite a while now!
That doesn't matter. Propaganda works. The message resonates. The voters will vote against their own interests over and over and over if they keep hearing something that resonates with what they feel.
PS: A great example of this are the thousands of unemployed people that lost their coal mining jobs. Trump lied through his teeth and told them they would get their mining jobs back. Hillary told them they could be retrained as tech support or whatever. They. Did. Not. Like. That. They wanted their jobs back! So they voted for Trump, who had zero chance of returning them to employment because they had been replaced by automation and larger, more powerful mining machines. Their jobs were gone permanently, so they doubled down by voting against the person who promised to pull them out of that hole. Sadly, this is a recurring theme in politics throughout the world.
[1] As an example, this is why they're mostly pro-gun! They know viscerally that if someone broke into their property, they'd have to defend themselves because the local police can't get there in time to save them.perception.