That's true. Part of the fun for me is seeing how people remember things differently. As they say, "Everyone is the hero of their own story." Bias is inevitable.
I kept a journal through my teen years and was astonished as an adult how I had misremembered some things-- important things that I knew I would never forget. Well, I changed them! Moved them in time and place, misremembered conversations, etc. If you want a really accurate account, you have to find someone who kept a journal, such as Michael Palin. I adore his accounts of George because they were set down at the time, not remembered.
Paul is particularly bad at remembering his "official" story so well it never occurs to him that it isn't right. He maintains that the Beatles made this condition that they would only go to America after they had a #1 hit, which is nonsense; the trip was set up long before. Yet he tells the story repeatedly, and I'm sure it's how he remembers it (or wants it remembered). (After all this time, would they really be able to remember what "really" happened vs the official story?) So it's fun to read the different views just for what they show about character.
This doesn't excuse bad writing or sloppy research. But I love first-person interviews or accounts. One of my favorite books was a hefty collection of news articles and interviews of the Beatles in the post break-up years: Keith Badman. The Beatles Diary Volume 2: After The Break-Up 1970-2001 Again, it was stories and interviews made at the time. So you can find out how easy-going George was immediately after the break-up, and which Beatle really didn't want to get back together when for what reason, on and on. In some cases, this is not the story they tell today. I don't think they're being dishonest; they just forgot. Heaven knows I don't have my life documented. But for accuracy, you really need to verify someone's assertion against the surviving record, before you can decide how much to trust them.