It’s encouraged to use things with a supply chain easily poisoned.

There’s the issue of a Heisenberg effect here - when a spectator is present, like a huge audit of something, nothing happens, and when a spectator isn’t present, there’s nobody to look every day in piles of constantly changed crap to detect if something happens.

Also not even easily poisoned, but easily denied. It’s about control. The militaries and producers of complex industrial equipment were the first to start doing this, however nuts that may seem. It’s useful to sell your allies a system they can use, but only when allowed. Or sell industrial equipment that can’t be smuggled to a third country without your permission.

These things - they are legal even morally, but at some point in discussion of them common good might arise as a thing in itself, separate from morality. For the common good such systems of control are clear poison.