If your farmer chose to ignore industry standard practices and agricultural regulations to prevent and contain such contamination at the source, they are indeed liable. And they can still issue a recall, and indeed must do so as soon as they learn of the problem.
Your vantage point is a bit too optimistic for reality. If it was not, we would not need courts.
For my example, assume no knowledge of extra risk by anyone on the line. If you'd rather, consider the cashier at the local burrito shop that was the final non-consumer hand to touch the contaminated food.
If, for instance, your burrito worker did something egregious, they could be held criminally liable, and depending on the specific situation, the employer could also be held civilly liable.
I say "depending on the situation" because it is the duty of the vendor to ensure best practices are followed: sanitary restrooms, soap and running, clean water for cleaning up, etc. And a nontrivial number of places do so because they know an inspector is coming at some point and they will suffer if they do not comply.
But it is harder to hold the vendor liable if all reasonable precautions and amenities are availed by the vendor, and all proper education, but the end of line worker decides to ignore all of it one day.
If they did something that was a standard part of their duty, such as assemble a burrito using certified ingredients to the best practices of the organization, then not so much.
I'll go even further, if the company reacted slowly to recall produce from their shelves after it was discovered that there was contamination, then the company should be held liable for some of the damages that resulted from the delay.
That gets obviously complicated to tease out damages that happened from before discovery. More, to me, I care more about healing the people that were impacted by the contamination as well as possible. If that means that we have to have a cost of business fund to make sure people can be attended to in the event of a disaster, then we should have such a fund.
You can get even more fun, though. Lets say you have a detection system that can reject produce if a threshold is passed on detected contamination. Why would the goal not be for this to fail in a "closed" position to minimize risk of contamination? It could cost more for the company to discard some inventory? Do we expect to have everything hand inspected and always signed off by a person? Even if it can easily be shown that is both more expensive for the company, and more risk of accidental contamination?
The mere fact that there are damages to extract means that someone was already damaged, not merely that we want to punish someone. If my neighbor is poisoned by food, I do not have standing to sue in my own capacity because my neighbor was poisoned. At this point, the moral question is whether or not you should be able to extract damages when you can show that you are damaged. Essentially every society has said "yes, of course," even though the specifics of what constitutes damage and recompense differs.
Why do people not universally (or at least generally) tend toward making Fail-Safe systems? I don't know, but they just do not. They must be compelled to.
Call it original sin or prevarication, the second law of thermodynamics, evolutionary inclination to save effort, whatever. But humans just default the opposite way of what you're saying.
Wow a local farm!!!! We must think of the plight of the local farmer! And not the multinational corporations!
Consider, if it is found that listeria contaminated the meat of a national Chain, Boar's Head, I want it recalled and for better systems in place to catch contamination. I also want the plant manager and executives who allowed for the massively unsanitary state to continue for years.
https://arstechnica.com/science/2024/09/10th-person-dead-in-...
The way you're talking , we should be going back to pre-Upton Sinclair The Jungle and letting our food run full of contaminants because why make any one person accountable for their willful addition of sawdust to their flour?
Now, I'm all for more directly holding companies responsible. Such that I think they probably deserve less protections than they almost certainly have here. But that is a different thing and, again, is unrelated to "a person taking accountability."
Consider, if it is found that salmonella contaminated the spinach of a local farm, I want it recalled and for better systems in place to catch contamination. I don't want to find the farmer that was responsible for the acre of land that introduced the contaminant.
I think this idea flows from some thought that people will put more effort into things that they think they could be held accountable for. In reality, that just isn't the case. People will instead stall and stall on things they think they could be held accountable on if things go south.
From my vantage, that style of "accountability" just leads to more and more red tape as you do what you can to line item identify who could have prevented something. That is not productive.