Public figures live on within the words they are remembered by. To understand the effect they had on history, their words need to be documented. No one is absolutely sure of exactly what Abraham Lincoln said in his most famous speech, the Gettysburg Address. Five known manuscripts exist, but all of them are slightly different. Every newspaper story from the day contains a different account.
In the case of modern presidents, for the official record, we rely upon transcriptions of all their speeches collected by the national government.
But in the case of Donald Trump, that historical record is likely to have a big gap. Almost 10% of the president’s total public speeches are excluded from the official record. And that means a false picture of the Trump presidency is being created in the official record for posterity.