The key lies in understanding the past perfect and the form is had + past participle.

The past perfect is considered as an early past. We go back for a moment whilst we are already talking about the past to clarify that something had already happened at that time we are talking about.

When I arrived at the party, Jane had gone.

Now think about that sentence -

NOW >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> PAST >>>>>>>>>>>>>>>>>>>>>>>>> EARLY PAST
(You arrive)-------------------------------------------------------------------------------------------- (Jane leaves)

Now your case -

You found out that had not known is not popular at all. Now considering this all, I think that when we talk about our perception such as knowing, the usage will be not that frequent as it'll mean that at that time (early past), that was not known to you. Anything hadn't makes it a special case. Let's get back to the same example to simplify it.

The things turns upside down if you use hadn't here.

When I arrived at the party, Jane hadn't wasn't gone (because, if she was there, it cannot be the early past!).

NOW >>>>>>>>>>>>>>>>>>>>>>>>>>> PAST >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> EARLY PAST
(You arrive, Jane wasn't gone) ---- (Jane did not go) -------------------------------------- (Jane hadn't gone)

If you see, it more depends on the context than the verbs you think that affect the use of hadn't + past participle. We can take some more examples and fit into this graph.

I checked Ngram and found that if you compare any did not (any verb) to had not (any verb), the use of did not is more frequent. The reason could be this only. What I tried to convey through the illustration. The Ngram clarifies that most of the times, we talk about the past and not early past (though it's not obsolete).

Swan's book describes another interesting thing...

The past perfect is common after past verbs of thinking and saying, to talk about things that had happened before the saying or thinking took place.

Examples -

I told her that I had finished (NOT... that I (have) finished)
I wondered who had left the door open

You can 'know' something at any time. You can realise something long after becoming aware of it, as 'knowing' requires a conscious thought to realise it. You can only 'notice' something when you're present, there and then, to be able to notice it.

Some people do say 'I didn't notice' however. The trend you're noticing might well just be the result of choosing a phrase that slips more elegantly from the tongue. This is possible but not likely.

It seems to be that the "did not" constructions refer to events that didn't necessarily take place at a specific time, and the "had not" constructions refer to events that either did or didn't take place at a specific time.

e.g. "I had not noticed/heard" -- the engine produced sounds at a specific time, but I wasn't paying attention, so I cannot answer affirmatively.

"I did not know" -- I lacked knowledge beforehand and nothing changed that (although the change could have occurred at any moment if someone had told me or I had researched it).

"I did not see" -- I was not looking at the thing in question, or I looked at it but didn't pay enough attention, though I could have looked at it at any other time.