Which is why a really good backdoor is a one line logic bug somewhere which is fiendishly difficult to trigger.

http://underhanded-c.org if people want examples of what could (and probably, somewhere, IS) being done.

Like the 2003 Linux kernel attempt https://lwn.net/Articles/57135/

Sure, however the problem that software is really hard also impacts bad actors. So it's probably at least as hard to write that one line logic bug and have it do exactly what you intended as to write equivalent real code that works precisely as intended.

Unrelated: as a dog/pointer lover i really like the term "to bird-dog the problem". Never heard of it (iam from germany though)

I’m from the U.S. and have never heard it either, and don’t understand what it means.

Pointing dogs (bird dogs) are made to point in the direction where they have perceived game. Good dogs are then not distracted by anything and stand there motionless, sometimes so far that they have to be carried away because they cannot turn away themselves.

It's somewhat regional, and it means to hunt down the target at the expense of everything else, as a dedicated hunting dog might.