I think people don't realize that "based on a true story/real life events" doesn't mean "we're trying to depict the story and all events surrounding it the way it totally happened". "Based on a true story/inspired by real events" generally means they take one aspect of some true event or a small portion of the story and then fill in around it with story that makes people more interested. And that makes it into an actual feature length film. Otherwise most of them would be people living regular life and then a singular but dramatic thing happening. You can't make an interesting 1.5-2 hour movie out of that most times. They also like to build up plot to make it more interesting because-surprise surprise- that's what makes money.