I don’t believe All of them kney they couldn’t get in. Whoever set this up probably told them the US needs them to harvest crops. And they know it’s the season.
That is believable, that a few thought they would be needed to harvest. But have they always needed to self-transport (walk) all the way up here in past years too? I would think harvesters would be transported by bus, round trip and with places to sleep, however spartan. I would expect the travel expenses to be paid by that corporate farmer. I could be completely wrong.