Farm trucks are a pathological case for electrification. They often have fairly extreme range requirements under adverse weather conditions and heavy loads. They spend much of their time far from the electrical grid, never mind a proper charging station. In some regions they have to account for being too far from a normal gas station, which is one of the reason you can buy barrels of fuel to bring with you or an extended tank.
But it doesn't matter because there aren't that many of them. Certainly not something we need to optimize for.
But the point isn't about farmers in particular, it's anyone who lives in a rural or suburban area without enough density for mass transit. Plumbers and real estate agents in those areas are not going to find a bus there to take. And there are a lot of those.