Is there a tendency among native speakers of English not to use "past perfect" for past conditional sentences? Perhaps they consider it "too correct"?

In the interaction

A: "Why didn't you tell me about the party Simon?"

B: "Because I didn't know there was a party. If I knew there was one, I would tell you."

B isn't just talking about that one party. They are stating a general rule that they will tell A about parties when they know about them. That's why their comment is being made in past subjunctive, rather than past perfect.

Here in Britain, anyway, there's much more than a tendency among native speakers not to use any tense they're not forced to.

Please remember, the UK Government admits about 20% of teenagers leave secondary school at best bordering on being functionally illiterate.

"Perhaps they consider it 'too correct' " is very much an understatement.

Many if not most UK speakers of English never consider anything of the kind and if they did, many would not understand what you're Asking, let alone any Answer.