That analogy doesn’t work at all because the Sow produces a finite (and rather small at that) number of piglets over a given timespan.

It’s more akin to you getting a piglet/sow elsewhere. Now your piglet/sow need is satisfied and you won’t buy anything from this farmer.

(Edit: And even then you took that piglet/sow away somewhere else, reducing supply there, which will make it more likely for this farmer to get a sale in the future.)

They have been debunked as lie detectors…
…But they can work at scaring the person testifying into giving away more information.

Sadly and logically, this is transshipment and if done to evade taxes by obfuscating place of origin, it is illegal. From what I heard, US customs does investigate that too, so it’s not just an “illegal in theory but nobody enforces it” kind of thing.