Why has bloody sunday been represented in such different ways?

Source B is from an eyewitness account, Edward Daly a Bishop, talks about how he ran away from the gunfire, he gives a bias but reliable account when he is interviewed by the Bloody Sunday investigation, as he is an  eyewitness he will know what it was like to see innocent people getting killed by the army and how terrifying it must have been, which could also imply why his view would be bias but he is asked much later on about the incident so he might not be able to recollect everything he saw. Daly mentions how innocent people were shot, he mentions how a boy 16-17 years old was running next to him laughing and smiling then he heard a gunshot and he looked around the “boy fell on his face” he states “I knew they were live bullets” he specifically tells them this piece of information because he knows how shocking it was as a teenager who thought it was not serious and even had his back t6o the army was then shot in the back, trying to give you a clear image that the army was brutal and did not aim according the “yellow card”

Source C is a news interview on ITN, 1972. Wilford is the officer of the 1st Battalion of Parachute regiment the interview says almost entirely the opposite to the other two sources. Wilford claims that the Gunmen where hit, but his excuse for not being able to find any weapons is that they must have been hidden by comrades. Even more controversial is that Wilford says that excessive force was used because they were being shot at. According to Wilford the Shooting were from the flats, but later knowledge proved, that the victims all died on the ground, proving the controversy because the people who were murdered were not in flats but helpless marchers trying to escape. This source would be the least reliable and by far the most bias, because Wilford has to make it seem that the people died were gunmen, and that the reason for using live ammunition was to protect themselves or him and the whole British Army would be frowned upon and in serious trouble. What led me to this view were his terrible excuses and inaccurate information, he uses terrible excuses like “we came under fire from flats the flats and petrol bombs” and inaccurate information such as “3 gunmen were hit, but no weapons were found”.

There are several reasons to such different interpretations as the incident would leave one side with terrible consequences, troops could be sent out of Ireland but if the Irish are found guilty for shootings and bombings, like Wilford claims, a lot of conflict would reside in Ireland once again. The correspondent would be the most reliable of the three, as his account would be the least bias as he knows the whole story of the previous conflicts and what troops had to put up with, but he would also know the families and feel sympathy towards them, but unlike the other two he does not need to give a bias report, he only needs to inform, this would give his account, source A, more reliability.