I know that in English we can sometimes "skip" the Present Perfect and use the Past Simple, like here:
John has won the election. Appropriate sort of the next day of the election night, when the speaker can suppose this is new information to the audience
John won the election. Appropriate in other cases (when this is not new information etc.)
Have you heard me? A more formal way, the result is important (we want to emphasize it), looks like a superior is asking a subordinate etc.
Did you hear me? A more informal way, when the result is not so relevant (we do not want to emphasize it) etc.
Now, the question is:
Do the same rules apply to the past perfect, is one forced to use the Past Perfect in every case, where the action was completed before the reference point?
People had had no tooth disease, until they started to eat sugar.
People had no tooth disease, until they started to eat sugar.
I saw the car taxing from the garage, luckily the driver had managed to start the engine
I saw the car taxing from the garage, luckily the driver managed to start the engine
This question is highly related to that one, and the accepted answer there actually raised my doubts on the matter, because I have never heard that the Past Perfect can be "skipped".
Thank you very much.