The slaughterhouse owners say that zero American citizens apply for these jobs

That is what they are telling you. Do you just trust everything someone says, without proof? I know I don't. A lot of these jobs are declining because Ai is taking over. Why pay someone to do something when you can have a machine do the same thing, for less money and it's faster.

The reason why most American's don't want farm work, is because they are overworked and underpaid. They are overworked and underpaid because they are illegals and they don't want to rock the boat and demand better wages, benefits and more rights as workers. How can you not see how this hurts the industry as a whole. Like I said you're looking at one side of a multifaceted situation.

You're basically saying that we should use illegals as slaves per your comment: "You'd probably have to pay $40/hr to get American citizens to do that job - plus you'd have to shorten the shifts, provide health insurance, air condition the slaughterhouses, follow OSHA regulations, etc. We're currently paying more like $10/hr to desperate immigrants and we don't do any of that."

Sorry but that is a shitty way to look at it, and a very wrong way in a lot of aspects. You're also overlooking the fact that Work Visas are a thing and a lot of people who are on Work Visas are also being given the short end of the stick because of the illegals taking over the positions they got their Visas for in the first place. You're displacing legal workers for illegals so we can pay them less and work them in terrible working conditions. Hell why not just bring back slavery while were at it, since it will be even cheaper. /s