Many, many situations of "lying to investigators" has been claimed to be an innocent mistake. No telling how many really were as it's 100% a judgement call of the investigators.
Until you've sat across from a pair of investigators, it's hard to guess how you'll respond to relatively simple questions.
I've run mock interview sessions for these and it's incredibly easy to trip someone up once you get them angry or get them agree to something you've purposely misstated.
It's not a judgment call of the investigators, it's a crime that you can plead not guilty to. I think the burden is on you to provide an example of someone who was actually convicted of this crime despite not having "knowingly and wilfully" lied.
Investigators - at least with the FBI, where I am familiar - don't record and are often discouraged from recording interviews. They take notes in the moment or summarize based on their memory some time after. Therefore what you said and how you meant it have gone through at least one interpretation before it makes it into any official record. And the interviewer is often not going to be the lead investigator on the case, adding another interpretation.
And that's assuming everyone is doing their best to give a complete and accurate statement+summary minimizing their own biases.
When it comes down to "knowingly and willfully" it is often a judgement call.
This is well-established legal understanding. Please read up on 302s:
Until you've sat across from a pair of investigators, it's hard to guess how you'll respond to relatively simple questions.
I've run mock interview sessions for these and it's incredibly easy to trip someone up once you get them angry or get them agree to something you've purposely misstated.