"Based On A True Story" ... Based???

Has anyone else ever noticed that after almost any event that captures the national spotlight, one of two things always seem to happen ... books are written, or movies are made? Both, I guess, are created to appease the public appetite for the shocking facts of what really transpired. But taking that a step further, how many of the facts become stretched, or even fabricated to meet the expectations of the audience? (AKA the "Hollywood effect") Suppose, for one minute, that the real story was nothing more than media hype. Gee, that would never happen in this country. (Remember Al Capone's vaults? Do I need to say more?) The actual parties involved in the original incident are paid quite handsomely to keep quiet, and let the director/writer take over. Well why not ... gotta pay the mortgage somehow, right? Who wouldn't? But from the viewer/readers perspective, I can't help but question the authenticity of the events portrayed in relevance to the actual situation that happened.