Still not sure what your point is. You seem stuck.

Nobody reads the tiny print in end credits. Viewers were told in opening credits that every detail except the names was true.

Someone went looking for the buried money and got themselves killed as a direct result of the statement in the opening credits.

Every single modern movie has that lawyer-require statement just in case they get sued.

No, real (by intent and marketing, not necessarily truthfulness) documentaries (which are modern movies) do not.

Movies that are actually intended as works of fiction (even if inspired by real events, and even if—well, given the purpose, especially if—including some characters retaining the names of those in the real events doing some of the things they actually did) have it.