If you go back even to Thatcher, of whom I am no fan, yes, politicians had to be a bit careful what they said in order to be elected, but once they were there, they (even Thatcher) were basically trying to do what they thought was best for the nation according to their views and priorities. Since about Blair, being elected and re-elected seems to have become the sole point of the exercise. I don't understand why people accept this as normal and reasonable. It's a recipe for having a completely rubbish country, and for being run by chronic attention-seekers with nothing else to offer. Here we are facing decisions and negotiations that are likely to have a profound effect on the economic well-being of the country for decades, with all the consequences that then has for the other services for which we look to government. Of all moments, this is when a remotely decent person would be putting getting that right in front of being able to enjoy their moment in showbiz for ugly people that bit longer. We are not getting that. Are we really to shrug our shoulders and say, well, that's okay, it's politics? It's dire.
"Bottom line is - no one can know the entire truth about anything unless they were there in person, when it happened."
It depends whether you are you are talking on the one hand in terms of some sort of absolute philosophical truth, or on the other hand about being able to be sure enough about something to make judgments for practical purposes.
Anyway, being there yourself is no guarantee, people notoriously mis-perceive and mis-remember things, you are dependent on your own faculties of perception and recollection, which are fallible.
It will often happen that someone is convicted of murder without another person having seen them carry out the act, because a jury is satisfied beyond reasonable doubt that they carried it out from circumstantial evidence. Circumstantial evidence can be very compelling. Hearsay evidence is much more dodgy; it can be helpful but there is much greater risk.